The mosaic on the right of the south polar region of Jupiter's moon Europa shows the northern 290 kilometers (180 miles) of a strike-slip fault named Astypalaea Linea. The entire fault is about 810 kilometers (500 miles) long, the size of the California portion of the San Andreas fault on Earth which runs from the California-Mexico border north to the San Francisco Bay.

The left mosaic shows the portion of the San Andreas fault near California's san Francisco Bay that has been scaled to the same size and resolution as the Europa image. Each covers an area approximately 170 by 193 kilometers(105 by 120 miles). The red line marks the once active central crack of the Europan fault (right) and the line of the San Andreas fault (left).

A strike-slip fault is one in which two crustal blocks move horizontally past one another, similar to two opposing lanes of traffic. The overall motion along the Europan fault seems to have followed a continuous narrow crack along the entire length of the feature, with a path resembling stepson a staircase crossing zones which have been pulled apart. The images show that about 50 kilometers (30 miles) of displacement have taken place along the fault. Opposite sides of the fault can be reconstructed like a puzzle, matching the shape of the sides as well as older individual cracks and ridges that had been broken by its movements.

Bends in the Europan fault have allowed the surface to be pulled apart. This pulling-apart along the fault's bends created openings through which warmer, softer ice from below Europa's brittle ice shell surface, or frozen water from a possible subsurface ocean, could reach the surface. This upwelling of material formed large areas of new ice within the boundaries of the original fault. A similar pulling apart phenomenon can be observed in the geological trough surrounding California's Salton Sea, and in Death Valley and the Dead Sea. In those cases, the pulled apart regions can include upwelled materials, but may be filled in mostly by sedimentary and erosional material deposited from above. Comparisons between faults on Europa and Earth may generate ideas useful in the study of terrestrial faulting.

One theory is that fault motion on Europa is induced by the pull of variable daily tides generated by Jupiter's gravitational tug on Europa. The tidal tension opens the fault; subsequent tidal stress causes it to move lengthwise in one direction. Then the tidal forces close the fault up again. This prevents the area from moving back to its original position. If it moves forward with the next daily tidal cycle, the result is a steady accumulation of these lengthwise offset motions.

Unlike Europa, here on Earth, large strike-slip faults such as the San Andreas are set in motion not by tidal pull, but by plate tectonic forces from the planet's mantle.

North is to the top of the picture. The Earth picture (left) shows a LandSat Thematic Mapper image acquired in the infrared (1.55 to 1.75 micrometers) by LandSat5 on Friday, October 20th 1989 at 10:21 am. The original resolution was 28.5 meters per picture element.

The Europa picture (right) is centered at 66 degrees south latitude and 195 degrees west longitude. The highest resolution frames, obtained at 40 meters per picture element with a spacecraft range of less than 4200 kilometers (2600 miles), are set in the context of lower resolution regional frames obtained at 200 meters per picture element and a range of 22,000 kilometers (13,600 miles). The images were taken on September 26, 1998 by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL HTTP://www.jpl.nasa.gov/galileo/sepo.

Voir l'image PIA01645: The San Andreas Fault and a Strike-slip Fault on Europa sur le site de la NASA.

PIA00540: Flows on Europa

The icy surface of Europa, one of the moons of Jupiter, was photographed by the Galileo spacecraft on its fourth orbit around Jupiter. The area shown here is about 77 miles (124 kilometers) by 115 miles (186 kilometers) across and shows features as small as a half a mile (800 meters) across. Thick, lobate flows, the first seen on Europa or any of the icy satellites of Jupiter, are visible in several areas, including the lower right quarter of the picture where one flow cuts across a prominent ridge. Most of the ridges on the left side of the picture appear to be partly buried or subdued by flows. The ice-rich surface of Europa suggests that the flows might also be ice, perhaps erupted onto the surface from the interior as viscous, glacierlike masses.

This picture was taken by the solid state imaging television camera on board the Galileo spacecraft at a distance of 39,191 miles (63,490 kilometers). The picture is centered at 319.5 degrees West, 5.11 degrees North; north is toward the top of the image with the sun shining from the right to the left.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the Galileo mission home page on the World Wide Web at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA00540: Flows on Europa sur le site de la NASA.

PIA00591: Europa Ice Rafts

PIA00596: Close-up of Europa's Trailing Hemisphere and similar scales on Earth

This is the second in a series of five products at increasing resolutions that compare images of various areas on Jupiter's icy moon Europa (top frame) to the same location on Earth, the San Francisco Bay area of California (bottom frame). Both images show areas of equal size, 100 by 140 kilometers (62 by 87 miles), and resolution, 180 meters (200 yards). This means that the smallest visible object is about a quarter of a mile across. North is to the top of the picture.

This complex terrain shows an area centered at 8 degrees north latitude, 275.4 degrees west longitude, in the trailing hemisphere. As Europa moves in its orbit around Jupiter, the trailing hemisphere is the portion which is always on the moon's backside opposite to its direction of motion. The complex ridge crossing the picture in the upper left corner is part of a feature that can be traced hundreds of miles across the surface of Europa, extending beyond the edge of the picture. The upper right part of the picture shows terrain that has been disrupted by an unknown process, superficially resembling blocks of sea ice during a springtime thaw. Also visible are semicircular mounds surrounded by shallow depressions. These might represent the intrusion of material punching through the surface from below and partial melting of Europa's icy crust.

In the San Francisco Bay area image, the level of detail is such that jigsaw puzzle like patterns of agricultural fields can be seen in the upper right corner and some levels of physical relief can be detected in the coastal mountain ranges. Also discernible at this resolution are the vast urban areas along the shores of the bay. Alcatraz Island appears as a tiny speck at center frame.

The Europa image was obtained from a range of 17,900 kilometers (11,100 miles) by the Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft on February 20th, 1997 (Universal Time). The San Francisco Bay area image, from the LandSat Thematic Mapper, has been reprocessed to match Galileo's resolution so as to offer a sense of the size of the features visible on Europa's surface.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA00596: Close-up of Europa's Trailing Hemisphere and similar scales on Earth sur le site de la NASA.

PIA01642: Cracks and Ridges Distorted by Europan Fault Motion

These cracks and ridges in the south polar region of Jupiter's moon Europa have been rotated into sigmoidal or "S" shapes by the motion of Astypalaea Linea, a strike-slip fault in the moon's icy surface. These cracks and ridges are located within Cyclades Macula, a region of the fault which has been pulled apart and created openings through which warmer, softer ice from below Europa's brittle ice shell surface, or frozen water from a possible subsurface ocean, could reach the surface. This upwelling of material formed large areas of new ice within the boundaries of the original fault. North is to the top of the picture. The once active fault structure is a barely visible line (right of center) that trends approximately north to south in this image.

An earlier northwest to southeast trending generation of rotated cracks underlies the more recent set. Such rotated structure is typical of a process known as "simple shear," and characterizes many large strike-slip faults on Earth. In this case, however, simple shear structures seem limited to the interior of the Cyclades Macula pull apart region and do not appear to border the elongate trunk of the fault, Astypalaea Linea. Comparisons between these structures related to faults on Europa and those on Earth may generate ideas useful in the study of terrestrial faulting.

The sun illuminates the surface from the top. The image, centered at 63 degrees south latitude and 191 degrees west longitude, covers an area approximately 15 by 10 kilometers (9 by 6 miles). The resolution is 40 meters (131 feet) per picture element. The images were taken on September 26, 1998 at a range of less than 4200 kilometers (2600 miles) by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URLhttp://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at URLhttp://www.jpl.nasa.gov/galileo/sepo.">http://www.jpl.nasa.gov/galileo/sepo.

Voir l'image PIA01642: Cracks and Ridges Distorted by Europan Fault Motion sur le site de la NASA.

PIA00598: Structurally Complex Surface of Europa and similar scales on Earth

This is the fourth in a series of five products at increasing resolutions that compare images of various areas on Jupiter's icy moon Europa (left frame) to the same location on Earth, the San Francisco Bay area of California (right frame). Both images show areas of equal size, 17 by 49 kilometers (11 by 30 miles), and resolution, 30 meters (100 feet). North is to the top of the picture.

The frame on the left is a mosaic of two images of Europa and shows the surface to be structurally complex. The sun illuminates the scene from the east, revealing complex overlapping ridges and fractures in the upper and lower portions of the frame, and rugged, more chaotic terrain in the center. Lateral faulting is revealed where ridges show offsets along their lengths (upper left of the frame). Missing ridge segments indicate obliteration of pre-existing materials and emplacement of new terrain (center of the frame).

The surface of San Francisco rivals that of Europa. In this 30 meter resolution comparison image, the complex pattern of city streets is clearly visible as are the many piers that line the water front district (upper right). This Bay area scene is also illuminated from the east. Notice the shadow of the Bay Bridge on the surface of the water as it makes its way to Oakland and the east bay. In the upper left corner, a ship can be seen making its way to the mouth of the bay.

The Europa image was obtained from a range of 3410 kilometers (2119 miles) by the Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft on December 19th, 1996 (Universal Time). The San Francisco Bay area image, from the LandSat Thematic Mapper, has been reprocessed to match Galileo's resolution so as to offer a sense of the size of the features visible on Europa's surface.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA00598: Structurally Complex Surface of Europa and similar scales on Earth sur le site de la NASA.

PIA01403: A closer look at Chaos on Europa

This mosaic of the Conamara Chaos region on Jupiter's moon, Europa, clearly indicates relatively recent resurfacing of Europa's surface. Irregularly shaped blocks of water ice were formed by the break up and movement of the existing crust. The blocks were shifted, rotated, and even tipped and partially submerged within a mobile material that was either liquid water, warm mobile ice, or an ice and water slush. The presence of young fractures cutting through this region indicates that the surface froze again into solid, brittle ice.

The background image in this picture was taken during Galileo's sixth orbit of Jupiter in February, 1997. Five very high resolution images which were taken during the spacecraft's twelfth orbit in December, 1997 provide an even closer look at some of the details. This mosaic shows some of the high resolution data inset into the context of this tumultuous region.

North is to the top of the picture, and the sun illuminates the scene from the east (right). The picture, centered at 9 degrees north latitude and 274 degrees west longitude, covers an area approximately 35 by 50 kilometers (20 by 30 miles). The finest details visible in the very high resolution insets are about 20 meters (22 yards) across, and in the background image, 100 meters (110 yards) across. The insets were taken on December 16, 1997, at ranges as close as 880 kilometers (550 miles) by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA01403: A closer look at Chaos on Europa sur le site de la NASA.

PIA00295: Dark Bands on Europa

Dark crisscrossing bands on Jupiter's moon Europa represent widespread disruption from fracturing and the possible eruption of gases and rocky material from the moon's interior in this four-frame mosaic of images from NASA's Galileo spacecraft. These and other features suggest that soft ice or liquid water was present below the ice crust at the time of disruption. The data do not rule out the possibility that such conditions exist on Europa today. The pictures were taken from a distance of 156,000 kilometers (about 96,300 miles) on June 27, 1996. Many of the dark bands are more than 1,600 kilometers (1,000 miles) long, exceeding the length of the San Andreas fault of California. Some of the features seen on the mosaic resulted from meteoritic impact, including a 30- kilometer (18.5 mile) diameter crater visible as a bright scar in the lower third of the picture. In addition, dozens of shallow craters seen in some terrains along the sunset terminator zone (upper right shadowed area of the image) are probably impact craters. Other areas along the terminator lack craters, indicating relatively youthful surfaces, suggestive of recent eruptions of icy slush from the interior. The lower quarter of the mosaic includes highly fractured terrain where the icy crust has been broken into slabs as large as 30 kilometers (18.5 miles) across. The mosaic covers a large part of the northern hemisphere and includes the north pole at the top of the image. The sun illuminates the surface from the left. The area shown is centered on 20 degrees north latitude and 220 degrees west longitude and is about as wide as the United States west of the Mississippi River. The Galileo mission is managed by NASA's Jet Propulsion Laboratory.

Voir l'image PIA00295: Dark Bands on Europa sur le site de la NASA.

PIA01404: Small Craters on Europa

This high resolution view of the Conamara Chaos region on Jupiter's icy moon, Europa, reveals craters which range in size from about 30 meters to over 450 meters (slightly over a quarter of a mile) in diameter. The large number of craters seen here is unusual for Europa. This section of Conamara Chaos lies inside a bright ray of material which was ejected by the large impact crater, Pwyll, 1000 kilometers (620 miles) to the south. The presence of craters within the bright ray suggests that many are secondaries which formed from chunks of material that were thrown out by the enormous energy of the impact which formed Pwyll.

North is to the upper right of the picture and the sun illuminates the surface from the east. The image, centered at 9 degrees latitude and 274 degrees longitude, covers an area approximately 8 by 4 kilometers (5 by 2.5 miles). The finest details that can be discerned in this picture are about 20 meters (66 feet) across. The images were taken on December 16, 1997 at a range of 960 kilometers (590 miles) by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA01404: Small Craters on Europa sur le site de la NASA.

PIA00851: Cross-cutting Relationships of Surface Features on Europa

This image of Jupiter's moon Europa shows a very complex terrain of ridges and fractures. The absence of large craters and the low number of small craters indicates that this surface is geologically young. The relative ages of the ridges can be determined by using the principle of cross-cutting relationships; i.e. older features are cross-cut by younger features. Using this principle, planetary geologists are able to unravel the sequence of events in this seemingly chaotic terrain to unfold Europa's unique geologic history.

The spacecraft Galileo obtained this image on February 20, 1997. The area covered in this image is approximately 11 miles (18 kilometers) by 8.5 miles (14 kilometers) across, near 15 North, 273 West. North is toward the top of the image, with the sun illuminating from the right.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA00851: Cross-cutting Relationships of Surface Features on Europa sur le site de la NASA.

PIA09361: Europa Rising

PIA01216: Very High Resolution Image of Icy Cliffs on Europa and Similar Scales on Earth (Providence, RI)

The top image is a very high resolution view of the Conamara Chaos region on Jupiter's moon Europa, showing an area where icy plates have been broken apart and moved around laterally. The top of this image is dominated by corrugated plateaus ending in icy cliffs over a hundred meters (a few hundred feet) high. Debris piled at the base of the cliffs. The bottom image is an aerial photograph of downtown Providence, Rhode Island at the same scale. The bright white circular feature in the top center of the Providence image is an indoor hockey rink, and one can find many craters in the Europa image about the same size. Blocks of debris which have fallen from the cliffs on the Europa image are about the same size as houses seen in the Providence image, and the largest blocks are almost as large as the Rhode Island state capitol building (large white building in upper left of Providence image). A fracture that runs horizontally across the center of the Europa image is about the same width as the freeway which runs along the bottom of the Providence image.

North is to the top right of the Europa image, and the sun illuminates the surface from the east. The Europa image is centered at approximately 9 degrees north latitude and 274 degrees west longitude. The images each cover an area approximately 1.7 kilometers by 4 kilometers (1 mile by 2.5 miles). The resolution is 9 meters (30 feet) per picture element. The Europa image was taken on December 16, 1997 at a range of 900 kilometers (540 miles) by the solid state imaging system on NASA's Galileo spacecraft.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/ galileo.

Voir l'image PIA01216: Very High Resolution Image of Icy Cliffs on Europa and Similar Scales on Earth (Providence, RI) sur le site de la NASA.

PIA01101: Topography on Europa....the Shadow knows

This image of Europa was taken by the Galileo spacecraft under "low-sun" illumination--the equivalent of taking a picture from a high altitude at sunrise or sunset. Note that in this image the topography of the terrain is emphasized. Planetary geologists use information from images acquired under a variety of lighting conditions to identify different types of structures and interpret how they formed. For example, the length of the shadow cast by a feature (e.g. a ridge or knob) is indicative of that feature's height. In this recent image, ridges and irregularly shaped knobs ranging in size from 5 kilometers across down to the limit of resolution (0.44 kilometers/pixel) can be seen. Measurements from shadow lengths indicate that features in this image range from tens of meters up to approximately one hundred meters in height.

The Galileo spacecraft acquired this image of Europa's surface during its third orbit around Jupiter. The image covers an area approximately 40 kilometers (25 miles) by 75 kilometers (45 miles), centered near 10S, 190W.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov.

Voir l'image PIA01101: Topography on Europa....the Shadow knows sur le site de la NASA.

PIA01211: Pwyll Crater on Europa

This enhanced color image of the region surrounding the young impact crater Pwyll on Jupiter's moon Europa was produced by combining low resolution color data with a higher resolution mosaic of images obtained on December 19, 1996 by the Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft. This region is on the trailing hemisphere of the satellite, centered at 11 degrees South and 276 degrees West, and is about 1240 kilometers across. North is toward the top of the image, and the sun illuminates the surface from the east.

The 26 kilometer diameter impact crater Pwyll, just below the center of the image, is thought to be one of the youngest features on the surface of Europa. The diameter of the central dark spot, ejecta blasted from beneath Europa's surface, is approximately 40 kilometers, and bright white rays extend for over a thousand kilometers in all directions from the impact site. These rays cross over many different terrain types, indicating that they are younger than anything they cross. Their bright white color may indicate that they are composed of fresh, fine water ice particles, as opposed to the blue and brown tints of older materials elsewhere in the image.

Also visible in this image are a number of the dark lineaments which are called "triple bands" because they have a bright central stripe surrounded by darker material. Scientists can use the order in which these bands cross each other to determine their relative ages, as they attempt to reconstruct the geologic history of Europa.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA01211: Pwyll Crater on Europa sur le site de la NASA.

PIA00746: Various Landscapes and Features on Europa

DESCRIPTIONS AND APPROXIMATE RESOLUTIONSRidges and Lineaments

27 meters/pixelTriple Bands

1.6 kilometers/pixelDark Spots

1.6 kilometers/pixel"Pull-apart" Terrain

1.6 kilometers/pixel"Raft" Terrain

250 meters/pixelFlows

225 meters/pixel"Puddle"

27 meters/pixelMottled Terrain

35 meters/pixelKnobs

1.6 kilometers/pixelPits

1.6 kilometers/pixelCrater

300 meters/pixelCrater Ejecta

1.4 kilometers/pixe "Macula"

600 meters/pixelIR-Bright/Dark Terrain

1.6 kilometers/pixelGlobal View

7 kilometers/pixel

These 15 frames show the great variety of surface features on Jupiter's icy moon, Europa, which have been revealed by the Galileo spacecraft Solid State Imaging (CCD) system during its first six orbits around Jupiter from June 1996 to February 1997. North is to the top of each of the images. The features seen on Europa's surface document both internal and external processes shaping the icy crust. Internal processes and the possible presence of liquid water beneath the ice are indicated by features such as "dark spots", lobe-shaped flow features, "puddles", "mottled terrain", knobs, pits, and the darker areas along ridges and triple bands.

Europa is subjected to constant tugging from the giant planet, Jupiter, as well as from its neighboring moons, Io and Ganymede. This causes "tidal" forces that affect Europa's interior and surface. Evidence for such forces includes ridges, fractures, wedge-shaped bands, and areas of "chaos." Some of these features result from alternate extension and compression buckling and pulling apart Europa's icy shell.

Impact craters document external effects on a planet's surface. Although present on Europa, impact craters are relatively scarce compared to the number seen on Ganymede, Callisto, and on the surfaces of most other "rocky" planets and moons in our solar system. This scarcity of craters suggests that the surface of Europa is very young. "Maculae" on Europa may be the scars from large impact events.

These images have resolutions from 27 meters (89 feet) to 7 kilometers (4.3 miles) per picture element (pixel) and were taken by Galileo at ranges of 2,500 kilometers (1,525 miles) to 677,000 kilometers (413,000 miles) from Europa.

Beginning with the upper left corner and moving left to right, top to bottom, the images show:

1. Ridges and lineaments crisscross the icy shell of Europa's surface. These are the most common landform on Europa and may represent either ejection of material from beneath its icy shell, or crumpling of the shell itself. Features as small as 54 meters (179 feet) across can be seen in this image, taken when Galileo was 2,550 kilometers (1,560 miles) from Europa.

2. Triple bands, seen by Voyager as linear features with a bright center and dark flanks, crisscross the surface of Europa. In high resolution Galileo images, these bands resolve into multiple ridges with diffuse darker deposits along the edges. Features as small as 3.2 kilometers (2 miles) across can be seen in this image, taken when Galileo was 155,000 kilometers (94,550 miles) from Europa.

3. Several "dark spots", areas of lower albedo (brightness) than the surrounding icy crust of Europa. These features, first identified in Voyager images, are seen to have diffuse outer margins and little topography. Features as small as 3.2 kilometers (2 miles) across can be seen in this image, taken when Galileo was 155,000 kilometers (94,550 miles) from Europa.

4. Wedge shaped bands of lower albedo than the surrounding areas. These areas appear to represent places where Europa's icy crust has been pulled apart and new material has filled in the area between the diverging ice sheets. Features as small as 3.2 kilometers (2 miles) across can be seen in this image, taken when Galileo was 155,000 kilometers (94,550 miles) from Europa.

5. An area known as "Conamara Chaos", characterized by polygonal sections of Europa's icy crust that broadly resemble icebergs. Individual ice RraftsS have been tilted, rotated and displaced from their original positions for distances of several kilometers. This terrain suggests that liquid water or ductile ice was present near the surface. Features as small as 500 meters (1,650 feet) across can be seen in this image, taken when Galileo was 17,936 kilometers (10,941 miles) from Europa.

6. Lobe shaped features that appear to be the icy equivalent of lava flows on Earth. Material has "erupted" through the icy shell and flowed over the surface of Europa for up to 30 kilometers (18 miles). Features as small as 450 meters (1,490 feet) across can be seen in this image, taken when Galileo was 17,684 kilometers (10,787 miles) from Europa.

7. A "puddle" of smooth material that appears to have buried parts of ridges. This feature is highly suggestive of liquid water or a water/ice slurry that locally flooded the European surface. The central crater is a coincidental feature produced by the subsequent impact of a meteor. Features as small as 54 meters (179 feet) across can be seen in this image, taken when Galileo was 2,491 kilometers (1,520 miles) from Europa.

8. A high resolution view of "mottled" terrain on Europa. This terrain, first discovered by Voyager was imaged at much higher resolution by Galileo. It is characterized by local darkening of the icy surface, in association with numerous small hills or "hummocks." The origin of this terrain remains enigmatic. Features as small as 70 meters (232 feet) across can be seen in this image, taken when Galileo was 3,344 kilometers (2,040 miles) from Europa.

9. Isolated hills or "knobs" on the surface of Europa. Although surface relief on Europa is typically very small (

Voir l'image PIA00746: Various Landscapes and Features on Europa sur le site de la NASA.

PIA01661: Large Impact Structures on Europa

The picture compares four large impact structures on Jupiter's icy moon, Europa. Clockwise, from top left, are Pwyll, Cilix, Tyre, and Mannann'an. Impact structures with diameters of more than 20 kilometers are rather rare on Europa. Tyre is most unusual. While the effective crater, which is somewhat larger than the prominent large bull's eye feature, is about 40 kilometers (25 miles) across, the entire structure is much larger. The concentric rings display relatively little relief. Some of the smaller craters near Tyre were formed by material ejected by and then redeposited from the impact which formed Tyre. One hypothesis for such characteristics is that the impactor which formed Tyre penetrated through an icy crust into a less brittle layer. While Pwyll, Cilix, and Mannann'an also display shallow crater depths for their size, they more closely resemble similar sized craters on two neighboring moons of Jupiter, Ganymede and Callisto. Perhaps the impactor did not punch through the upper crust during these events. This might have been the case if the impacting body was smaller or weaker than in the case of Tyre or if the crust was thinner at the location of Tyre during the impact event.

North is to the top of the picture. The sun illuminates the surfaces from the right, except for Tyre, where the sun illuminates the surface from the left. The horizontal and vertical grey lines in the Tyre mosaic indicate gaps in the data received for this image. The Pwyll image was taken on December 16, 1997, Cilix on May 31, 1998,Tyre on March 29, 1998, and Mannann'an on March 29, 1998. All images were taken by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.

Voir l'image PIA01661: Large Impact Structures on Europa sur le site de la NASA.

PIA00518: Ridges on Europa

This view of Jupiter's moon Europa shows a portion of the surface that has been highly disrupted by fractures and ridges. This picture covers an area about 238 kilometers (150 miles) wide by 225 kilometers (140 miles), or about the distance between Los Angeles and San Diego. Symmetric ridges in the dark bands suggest that the surface crust was separated and filled with darker material, somewhat analogous to spreading centers in the ocean basins of Earth. Although some impact craters are visible, their general absence indicates a youthful surface. The youngest ridges, such as the two features that cross the center of the picture, have central fractures, aligned knobs, and irregular dark patches. These and other features could indicate cryovolcanism, or processes related to eruption of ice and gases.

This picture, centered at 16 degrees south latitude, 196 degrees west longitude, was taken at a distance of 40,973 kilometers (25,290 mi) on November 6, 1996 by the Galileo spacecraft solid state imaging television camera onboard the Galileo spacecraft during its third orbit around Jupiter.

The Galileo mission is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, Washington, D.C.

This image and other images and data received from Galileo are posted on the Galileo mission home page on the World Wide Web at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo.

Voir l'image PIA00518: Ridges on Europa sur le site de la NASA.

PIA00849: Ridges and Fractures on Europa

PIA03878: Ruddy "Freckles" on Europa

Reddish spots and shallow pits pepper the enigmatic ridged surface of Europa in this view combining information from images taken by NASA's Galileo spacecraft during two different orbits around Jupiter.

The spots and pits visible in this region of Europa's northern hemisphere are each about 10 kilometers (6 miles) across. The dark spots are called "lenticulae," the Latin term for freckles. Their similar sizes and spacing suggest that Europa's icy shell may be churning away like a lava lamp, with warmer ice moving upward from the bottom of the ice shell while colder ice near the surface sinks downward. Other evidence has shown that Europa likely has a deep melted ocean under its icy shell. Ruddy ice erupting onto the surface to form the lenticulae may hold clues to the composition of the ocean and to whether it could support life.

The image combines higher-resolution information obtained when Galileo flew near Europa on May 31, 1998, during the spacecraft's 15th orbit of Jupiter, with lower-resolution color information obtained on June 28, 1996, during Galileo's first orbit.

The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/.

Voir l'image PIA03878: Ruddy "Freckles" on Europa sur le site de la NASA.

PIA01503: Europa's Fractured Surface

PIA01504: Europa's Evening Terminator

PIA01181: Europa Ice Cliffs-High Resolution

This view of the Conamara Chaos region on Jupiter's moon Europa shows cliffs along the edges of high-standing ice plates. The washboard texture of the older terrain has been broken into plates which are separated by material with a jumbled texture. The cliffs themselves are rough and broadly scalloped, and smooth debris shed from the cliff faces is piled along the base. For scale, the height of the cliffs and size of the scalloped indentations are comparable to the famous cliff face of Mount Rushmore in South Dakota.

This image was taken on December 16, 1997 at a range of 900 kilometers (540 miles) by the solid state imaging system (camera) on NASA's Galileo spacecraft. North is to the top right of the picture, and the sun illuminates the surface from the east. This image, centered at approximately 8 degrees north latitude and 273 degrees west longitude, covers an area approximately 1.5 kilometers by 4 kilometers (0.9 miles by 2.4 miles). The resolution is 9 meters (30 feet) per picture element.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/ galileo.

Voir l'image PIA01181: Europa Ice Cliffs-High Resolution sur le site de la NASA.

PIA00875: Thera and Thrace Macula on Europa

This image of Europa's southern hemisphere was obtained by the solid state imaging (CCD) system on board NASA's Galileo spacecraft during its sixth orbit of Jupiter. The upper left portion of the image shows the southern extent of the "wedges" region, an area that has undergone extensive disruption. South of the wedges, the eastern extent of Agenor Linea (nearly 1000 kilometers in length) is also visible. Thera and Thrace Macula are the dark irregular features southeast of Agenor Linea. This image can be used by scientists to build a global map of Europa by tying such Galileo images together with images from 1979 during NASA's Voyager mission. Such lower resolution images also provide the context needed to interpret the higher resolution images taken by the Galileo during both its nominal mission and the upcoming Europa mission. North is to the top of the picture and the sun illuminates the surface from the right. The image, centered at -40 latitude and 180 longitude, covers an area approximately 675 by 675 kilometers. The finest details that can be discerned in this picture are about 3.3 kilometers across. The images were taken on Feb 20, 1997 at 12 hours, 55 minutes, 34 seconds Universal Time when the spacecraft was at a range of 81,707 kilometers.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA00875: Thera and Thrace Macula on Europa sur le site de la NASA.

PIA01296: Europa "Ice Rafts" in Local and Color Context

This image of Jupiter's icy satellite Europa shows surface features such as domes and ridges, as well as a region of disrupted terrain including crustal plates which are thought to have broken apart and "rafted" into new positions. The image covers an area of Europa's surface about 250 by 200 kilometer (km) and is centered at 10 degrees latitude, 271 degrees longitude. The color information allows the surface to be divided into three distinct spectral units. The bright white areas are ejecta rays from the relatively young crater Pwyll, which is located about 1000 km to the south (bottom) of this image. These patchy deposits appear to be superposed on other areas of the surface, and thus are thought to be the youngest features present. Also visible are reddish areas which correspond to locations where non-ice components are present. This coloring can be seen along the ridges, in the region of disrupted terrain in the center of the image, and near the dome-like features where the surface may have been thermally altered. Thus, areas associated with internal geologic activity appear reddish. The third distinct color unit is bright blue, and corresponds to the relatively old icy plains.

This product combines data taken by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft during three separate flybys of Europa. Low resolution color data (violet, green, and 1 micron) acquired in September 1996 were combined with medium resolution images from December 1996, to produce synthetic color images. These were then combined with a high resolution mosaic of images acquired in February 1997.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA01296: Europa "Ice Rafts" in Local and Color Context sur le site de la NASA.

PIA00589: Mosaic of Europa's Ridges, Craters

This view of the icy surface of Jupiter's moon, Europa, is a mosaic of two pictures taken by the Solid State Imaging system on board the Galileo spacecraft during a close flyby of Europa on February 20, 1997. The pictures were taken from a distance of 2,000 kilometers (1,240 miles). The area shown is about 14 kilometers by 17 kilometers (8.7 miles by 10.6 miles), and has a resolution of 20 meters (22 yards) per pixel. Illumination is from the right (east). The picture is centered at about 14.8 north latitude, 273.8 west longitude, in Europa's trailing hemisphere.

One of the youngest features seen in this area is the double ridge cutting across the picture from the lower left to the upper right. This double ridge is about 2.6 kilometers (1.6 miles) wide and stands some 300 meters (330 yards) high. Small craters are most easily seen in the smooth deposits along the south margin of the prominent double ridge, and in the rugged ridged terrain farther south. The complexly ridged terrain seen here shows that parts of the icy crust of Europa have been modified by intense faulting and disruption, driven by energy from the planet's interior.

The Jet Propulsion Laboratory, Pasadena, CA, manages the mission for NASA's Office of Space Science, Washington D.C. This image and other images and data received from Galileo are posted on the World Wide Web Galileo mission home page at: http://galileo.jpl.nasa.gov.

Voir l'image PIA00589: Mosaic of Europa's Ridges, Craters sur le site de la NASA.

PIA00587: Close-up of Europa's Trailing Hemisphere

This complex terrain on Jupiter's moon, Europa, shows an area centered at 8 degrees north latitude, 275.4 degrees west longitude, in the trailing hemisphere. As Europa moves in its orbit around Jupiter, the trailing hemisphere is the portion which is always on the moon's backside opposite to its direction of motion. The area shown is about 100 kilometers by 140 kilometers (62 miles by 87 miles). The complex ridge crossing the picture in the upper left corner is part of a feature that can be traced hundreds of miles across the surface of Europa, extending beyond the edge of the picture. The upper right part of the picture shows terrain that has been disrupted by an unknown process, superficially resembling blocks of sea ice during a springtime thaw. Also visible are semicircular mounds surrounded by shallow depressions. These might represent the intrusion of material punching through the surface from below and partial melting of Europa's icy crust. The resolution of this image is about 180 meters (200 yards); this means that the smallest visible object is about a quarter of a mile across.

This picture of Europa was taken by Galileo's Solid State Imaging system from a distance of 17,900 kilometers (11,100 miles) on the spacecraft's sixth orbit around Jupiter, on February 20, 1997.

The Jet Propulsion Laboratory, Pasadena, CA, manages the mission for NASA's Office of Space Science, Washington D.C. This image and other images and data received from Galileo are posted on the World Wide Web Galileo mission home page at http://galileo.jpl.nasa.gov.

Voir l'image PIA00587: Close-up of Europa's Trailing Hemisphere sur le site de la NASA.

PIA01653: Rugged Terrain on Europa

This mosaic of an area just southeast of the Tyre multi-ring structure on Jupiter's moon Europa combines two sets of images taken by NASA's Galileo spacecraft. Features in this area include pits, plains, and regions of chaotic terrain. The circular to oval shaped pits that contain dark material are secondary craters formed by debris from the Tyre impact. While the origin of the dark material is uncertain, it could be subsurface material that was excavated by impacts or a deposit left behind as surface ice turned to vapor. Two types of plains can be distinguished: lineated and ridged. Ridged plains are composed of numerous small ridges which trend from northwest to southeast while lineated plains appear finer in texture with more closely spaced north to south trending ridges. Two types of chaotic terrain can be distinguished: hummocky and blocky. Hummocky chaos regions appear to contain very fine textured matrix material with a few small "rafts" that are commonly seen in other chaos regions. Blocky chaos regions contain the large (greater than 2 kilometers or 1.25 miles across) "rafts" of the pre-existing crustal material which are similar to those seen in the Conamara Chaos region of Europa.

North is to the top of the image and the sun illuminates the surface from the left. The image is in an orthographic projection, centered at 13 degrees north latitude and 110 degrees west longitude, and covers an area approximately 45 by 64 kilometers (28 by 40 miles). The resolution is about 30 meters (100 feet) across. The images were taken on May 31, 1998 at a range of approximately 4200 kilometers (2625 miles) by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission or NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URLhttp://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo.

Voir l'image PIA01653: Rugged Terrain on Europa sur le site de la NASA.

PIA01125: Regional Mosaic of Chaos and Gray Band on Europa

This mosaic of part of Jupiter's moon, Europa, shows a region that is characterized by mottled (dark and splotchy) terrain. The images in this mosaic were obtained by Solid State Imaging (CCD) system on NASA's Galileo spacecraft during its eleventh orbit around Jupiter. North is to the top of the image, and the sun illuminates the scene from the right. Prior to obtaining these pictures, the age and origin of mottled terrain were not known. As seen here, the mottled appearance results from areas of the bright, icy crust that have been broken apart (known as "chaos" terrain), exposing a darker underlying material. This terrain is typified by the area in the upper right-hand part of the image. The mottled terrain represents some of the most recent geologic activity on Europa. Also shown in this image is a smooth, gray band (lower part of image) representing a zone where the Europan crust has been fractured, separated, and filled in with material derived from the interior. The chaos terrain and the gray band show that this satellite has been subjected to intense geological deformation.

The mosaic, centered at 2.9 degrees south latitude and 234.1 degrees west longitude, covers an area of 365 kilometers by 335 kilometers (225 miles by 210 miles). The smallest distinguishable features in the image are about 460 meters (1500 feet) across. These images were obtained on November 6, 1997, when the Galileo spacecraft was approximately 21,700 kilometers (13,237 miles) from Europa.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. JPL is a division of California Institute of Technology.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo home page at URL http://galileo.jpl.nasa.gov. Background information and educational context can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA01125: Regional Mosaic of Chaos and Gray Band on Europa sur le site de la NASA.

PIA00459: Europa During Voyager 2 Closest Approach

PIA00850: Europa Under Stress

This high resolution image of the icy plains on Europa shows multiple sets of cross-cutting ridges. Many of these ridges are cut by younger fractures. Fractures that display relative motion are known as faults; several faults showing horizontal motion, like the San Andreas Fault in California, are seen here.

Faults and ridges give planetary geologists clues to the stresses within the crust at the time of formation. Ridges typically form as a result of compression. The orientation of the compressive stress is perpendicular to the strike (long axis) of the ridge. In contrast, fractures form as a result of tensional stresses that crack the brittle crust. These features indicate that the surface of Europa has experienced repeated episodes of tension and compression throughout its history.

This image is approximately 12 kilometers (7 miles) by 15 kilometers (9 miles) across, centered near 15N, 273W. The Galileo spacecraft obtained this image on February 20, 1997 during its sixth orbit of Jupiter from a distance of 2000 kilometers (1240 miles). North is toward the top of the image, with the sun illuminating the surface from the right.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA00850: Europa Under Stress sur le site de la NASA.

PIA00294: Europa's Active Surface

PIA01405: A Dark Spot on Europa

This view taken by NASA's Galileo spacecraft of Jupiter's icy moon Europa focuses on a dark, smooth region whose center is the lowest area in this image. To the west (left), it is bounded by a cliff and terraces, which might have been formed by normal faulting. The slopes toward the east (right) leading into the dark spot are gentle.

Near the center of the dark area, it appears the dark materials have covered some of the bright terrain and ridges. This suggests that when the dark material was deposited, it may have been a fluid or an icy slush.

Only a few impact craters are visible, with some of them covered or flooded by dark material. Some appear in groups, which may indicate that they are secondary craters formed by debris excavated during a larger impact event. A potential source for these is the nearby crater Mannann`an.

North is to the top of the picture which is centered at 1 degree south latitude and 225 degrees west longitude. The images in this mosaic have been re-projected to 50 meters (55 yards) per picture element. They were obtained by the Solid State Imaging (SSI) system on March 29, 1998, during Galileo's fourteenth orbit of Jupiter, at ranges as close as 1940 kilometers (1,200 miles) from Europa.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA01405: A Dark Spot on Europa sur le site de la NASA.

PIA00599: Close-up of Europa's Surface and similar scales on Earth

This is the fifth in a series of products at increasing resolutions that compare images of various areas on Jupiter's moon Europa (top frame) to the same location on Earth, the San Francisco Bay area of California (bottom frame). Both images show areas of equal size, 13 by 18 kilometers (8 by 11 miles), and resolution, 26 meters (28 yards). North is to the top of the picture.

In this close-up view of Europa's icy surface, a flat smooth area about 3.2 kilometers (2 miles) across is seen in the left part of the picture. This area resulted from flooding by a fluid which erupted onto the surface and buried sets of ridges and grooves. The smooth area contrasts with a distinctly rugged patch of terrain farther east, to the right of the prominent ridge system running down the middle of the picture. Eruptions of material onto the surface, crustal disruption, and the formation of complex networks of folded and faulted ridges show that significant energy was available in the interior of Europa. The Sun illuminates the scene from the east (right).

The San Francisco Bay area image helps to give a sense of scale to the predominant features in the Europa image above. Both the "flat smooth area" and the contrasting "rugged patch" are sufficiently large to cover all of downtown San Francisco. The Golden Gate Bridge, if on Europa's surface, would be long enough to span each of those features as well.

The Europa image was obtained from a range of 2500 kilometers (1600 miles) by the Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft on December 19th, 1996 (Universal Time). The San Francisco Bay area image, from the LandSat Thematic Mapper, has been reprocessed to match Galileo's resolution so as to offer a sense of the size of the features visible on Europa's surface.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA00599: Close-up of Europa's Surface and similar scales on Earth sur le site de la NASA.

PIA00366: Europa - Mosaic

PIA00597: Europa Ice Rafts and similar scales on Earth

This is the third in a series of five products at increasing resolutions that compare images of various areas on Jupiter's moon Europa (top frame) to the same location on Earth, the San Francisco Bay area of California (bottom frame). Both images show areas of equal size, 34 by 42 kilometers (21 by 26 miles), and resolution, 54 meters (59 yards). North is to the top of the picture.

This high resolution image shows Europa's ice-rich crust with crustal plates ranging up to 13 kilometers (8 miles) across, which have been broken apart and "rafted" into new positions, superficially resembling the disruption of pack-ice on polar seas during spring thaws on Earth. The size and geometry of these features suggest that motion was enabled by ice-crusted water or soft ice close to the surface at the time of disruption. This Europa image is centered at 9.4 degrees north latitude, 274 degrees west longitude,

The San Francisco Bay portion of this image pair helps to give the viewer some sense of scale as it relates to the size of the Europa "ice rafts." Look, for example, at the cratered "ice raft" in the lower left hand portion of the Europa image. Compare that to such features in the Bay area image as Treasure Island Naval Station, (center frame) and the San Francisco International Airport (bottom right). Also in this image, at 54 meters resolution, structural features such as the Golden Gate Bridge and the Bay Bridge are clearly visible.

The Europa image was obtained from a range of 5,340 kilometers (3,320 miles) by the Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft on February 20th, 1997 (Universal Time). The San Francisco Bay area image, from the LandSat Thematic Mapper, has been reprocessed to match Galileo's resolution so as to offer a sense of the size of the features visible on Europa's surface.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA00597: Europa Ice Rafts and similar scales on Earth sur le site de la NASA.

PIA01643: A Record of Crustal Movement on Europa

This view of the south polar region of Jupiter's moon Europa shows part of a gray band that formed as plates on the icy surface separated and material filled in the widening gap. North is to the top of the picture. In the center of the image, a gently curving linear crack runs north to south and appears to be the location where the fault originally opened. Successive layers, like tree rings, form as material enters the gap periodically from below and hardens.

The relative motion of the two opposing sides of the band is mostly "strike-slip," where two crustal blocks move horizontally past one another, similar to two opposing lanes of traffic. However, since this motion is not exactly parallel to the active crack, the opposite sides also pull apart to create openings through which warmer, softer ice from below Europa's brittle ice shell surface, or frozen water from a possible subsurface ocean, could reach the surface. The band surface accumulates layer by layer. A rough symmetry with respect to the active central linear crack can be seen in these layers.

The large, segmented crack paralleling the west (left) side of the band cuts the original north to south fault shown in the center of the image. This suggests that the central fault has not been active since the large, segmented crack formed.

The curved, lined area is a small part of a much larger strike-slip fault called Astypalaea Linea. This fault extends over 800 kilometers (500 miles), roughly the distance of the portion of California's San Andreas fault from the Mexican border to the San Francisco Bay. Galileo images show that the Europan fault has slipped about 50 kilometers (30 miles).

The Sun illuminates the surface from the top. The image, centered at 66 degrees south latitude and 195 degrees west longitude, covers an area approximately 24 by 16 kilometers (15 by 10 miles). The resolution is 40 meters (131 feet) per picture element. The images were taken on September 26, 1998 at a range of less than 4,200 kilometers (2,600 miles) by Galileo's solid-state imaging system.

Voir l'image PIA01643: A Record of Crustal Movement on Europa sur le site de la NASA.

PIA01644: San Andreas-sized Strike-slip Fault on Europa

This mosaic of the south polar region of Jupiter's moon Europa shows the northern 290 kilometers (180 miles) of a strike-slip fault named Astypalaea Linea. The entire fault is about 810 kilometers (500 miles) long, about the size of the California portion of the San Andreas fault, which runs from the California-Mexico border north to the San Francisco Bay.

In a strike-slip fault, two crustal blocks move horizontally past one another, similar to two opposing lanes of traffic. Overall motion along the fault seems to have followed a continuous narrow crack along the feature's entire length, with a path resembling steps on a staircase crossing zones that have been pulled apart. The images show that about 50 kilometers (30 miles) of displacement have taken place along the fault. The fault's opposite sides can be reconstructed like a puzzle, matching the shape of the sides and older, individual cracks and ridges broken by its movements.

The red line marks the once active central crack of the fault. The black line outlines the fault zone, including material accumulated in the regions which have been pulled apart.

Bends in the fault have allowed the surface to be pulled apart. This process created openings through which warmer, softer ice from below Europa's brittle ice shell surface, or frozen water from a possible subsurface ocean, could reach the surface. This upwelling of material formed large areas of new ice within the boundaries of the original fault. A similar pulling-apart phenomenon can be observed in the geological trough surrounding California's Salton Sea, in Death Valley and the Dead Sea. In those cases, the pulled-apart regions can include upwelled materials, but may be filled mostly by sedimentary and eroded material from above.

One theory is that fault motion on Europa is induced by the pull of variable daily tides generated by Jupiter's gravitational tug on Europa. Tidal tension opens the fault and subsequent tidal stress causes it to move lengthwise in one direction. Then tidal forces close the fault again, preventing the area from moving back to its original position. Daily tidal cycles produce a steady accumulation of lengthwise offset motions. Here on Earth, unlike Europa, large strike-slip faults like the San Andreas are set in motion by plate tectonic forces.

North is to the top of the picture and the sun illuminates the surface from the top. The image, centered at 66 degrees south latitude and 195 degrees west longitude, covers an area approximately 300 by 203 kilometers(185 by 125 miles). The pictures were taken on September 26, 1998by Galileo's solid-state imaging system.

Voir l'image PIA01644: San Andreas-sized Strike-slip Fault on Europa sur le site de la NASA.

PIA00541: Macula on Europa

This image of Europa, an icy satellite of Jupiter about the size of the Earth's Moon, was obtained from a range of 7415 miles (11933 kilometers) by the Galileo spacecraft during its fourth orbit around Jupiter and its first close pass of Europa. The image spans 30 miles by 57 miles (48 km by 91 km) and shows features as small as 800 feet (240 meters) across. The large circular feature centered in the upper middle of the image is called a macula, and could be the scar of a large meteorite impact. The surface of Europa is composed mostly of water ice, so large impact craters on Europa could look different from large bowl-shaped depressions formed by impact into rock, such as on the Moon. On Europa's icy surface, the original impact crater has been modified into a central zone of rugged topography surrounded by circular fractures which reflect adjustments to stress in the surrounding icy crust.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

PIA00590: Europa Triple Band

This picture of Europa, a moon of Jupiter, was obtained on February 20, 1997, by the Solid State Imaging system onboard the Galileo spacecraft during its sixth orbit around Jupiter. The area is centered at 9.3 degrees north latitude, 275.7 degrees west longitude, on the trailing hemisphere of Europa. As Europa moves in its orbit around Jupiter, the trailing hemisphere is the portion which is always on the moon's backside opposite to its direction of motion. The area depicted is about 32 kilometers by 40 kilometers (20 miles by 25 miles). Resolution is 54 meters (59 yards). The Sun illuminates the scene from the right (east).

A section of a triple band crosses the upper left of the picture and extends for hundreds of miles across the surface. Triple bands derive their name from their appearance at lower resolution as a narrow bright band flanked by a pair of darker bands. At the high resolution of this picture, however, the triple band is much more complex and is composed of a system of ridges 6 kilometers (4 miles) across. Some ridges reach heights of about 180 meters (200 yards). Other features include a hill in the center of the picture about 480 meters (500 yards) high. Two mounds about 6 kilometers across (4 miles) are seen in the bottom of the picture. The ridges, hills and mounds probably all represent uplifts of the icy crust of Europa by processes originating from the interior.

PIA00586: Pwyll Crater on Europa

PIA00588: Europa Ridges, Hills and Domes

This moderate-resolution view of the surface of one of Jupiter's moons, Europa, shows the complex icy crust that has been extensively modified by fracturing and the formation of ridges. The ridge systems superficially resemble highway networks with overpasses, interchanges and junctions. From the relative position of the overlaps, it is possible to determine the age sequence for the ridge sets. For example, while the 8-kilometer-wide (5-mile) ridge set in the lower left corner is younger than most of the terrain seen in this picture, a narrow band cuts across the set toward the bottom of the picture, indicating that the band formed later. In turn, this band is cut by the narrow 2- kilometer-wide (1.2-mile) double ridge running from the lower right to upper left corner of the picture. Also visible are numerous clusters of hills and low domes as large as 9 kilometers (5.5 miles) across, many with associated dark patches of non-ice material. The ridges, hills and domes are considered to be ice-rich material derived from the subsurface. These are some of the youngest features seen on the surface of Europa and could represent geologically young eruptions.

This area covers about 140 kilometers by 130 kilometers (87 miles by 81 miles) and is centered at 12.3 degrees north latitude, 268 degrees west longitude. Illumination is from the east (right side of picture). The resolution is about 180 meters (200 yards) per pixel, meaning that the smallest feature visible is about a city block in size. The picture was taken by the Solid State Imaging system on board the Galileo spacecraft on February 20, 1997, from a distance of 17,700 kilometers (11,000 miles) during its sixth orbit around Jupiter.

The Jet Propulsion Laboratory, Pasadena, CA, manages the mission for NASA's Office of Space Science, Washington D.C. This image and other images and data received from Galileo are posted on the World Wide Web Galileo mission home page at http://galileo.jpl.nasa.gov.

Voir l'image PIA00588: Europa Ridges, Hills and Domes sur le site de la NASA.

PIA01180: Highest Resolution Image of Europa

During its twelfth orbit around Jupiter, on Dec. 16, 1997, NASA's Galileo spacecraft made its closest pass of Jupiter's icy moon Europa, soaring 200 kilometers (124 miles) kilometers above the icy surface. This image was taken near the closest approach point, at a range of 560 kilometers (335 miles) and is the highest resolution picture of Europa that will be obtained by Galileo. The image was taken at a highly oblique angle, providing a vantage point similar to that of someone looking out an airplane window. The features at the bottom of the image are much closer to the viewer than those at the top of the image. Many bright ridges are seen in the picture, with dark material in the low-lying valleys. In the center of the image, the regular ridges and valleys give way to a darker region of jumbled hills, which may be one of the many dark pits observed on the surface of Europa. Smaller dark, circular features seen here are probably impact craters.

North is to the right of the picture, and the sun illuminates the surface from that direction. This image, centered at approximately 13 degrees south latitude and 235 degrees west longitude, is approximately 1.8 kilometers (1 mile) wide. The resolution is 6 meters (19 feet) per picture element. This image was taken on December 16, 1997 by the solid state imaging system camera on NASA's Galileo spacecraft.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/ galileo.

Voir l'image PIA01180: Highest Resolution Image of Europa sur le site de la NASA.

PIA00874: Europa's Leading Hemisphere

This image of Europa's leading hemisphere was obtained by the solid state imaging (CCD) system on board NASA's Galileo spacecraft during its seventh orbit of Jupiter. In the upper left part of the image is Tyre, a multi-ringed structure that may have formed as a result of an ancient impact. Also visible are numerous lineaments that extend for over 1000 kilometers. The limb, or edge, of Europa in this image can be used by scientists to constrain the radius and shape of the satellite. North is to the top of the picture and the sun illuminates the surface from the right. The image, centered at -40 latitude and 180 longitude, covers an area approximately 2000 by 1300 kilometers. The finest details that can be discerned in this picture are about 6.6 kilometers across. The images were taken on April 3, 1997 at 17 hours, 42 minutes, 19 seconds Universal Time when the spacecraft was at a range of 31,8628 kilometers.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA00874: Europa's Leading Hemisphere sur le site de la NASA.

PIA00723: Context of Europa images from Galileo

PIA01970: Europa from 2,869,252 kilometers

PIA00846: NIMS E4 Observations of Europa Trailing Hemisphere

This image shows the Near Infrared Mapping Spectrometer (NIMS) observations of selected areas of Europa's trailing hemisphere during the Galileo E4 encounter on 19 December 1996. The NIMS data are projected onto a Voyager mosaic created from images taken in 1979. The spatial resolution of the NIMS images is approximately 3 km/pixel, four times better than those from Voyager. These NIMS observations are designed to search for mineralogical differences between high and low albedo regions. Observation E4ENSUCOMP03, for example, targets a series of double linea and the surrounding area in the northern latitudes of Europa. The linea seen in the visible by Voyager can be traced through the NIMS images, shown here at a 0.7 microns, a wavelength beyond human vision. The NIMS spectra show the surface of Europa is coated with a combination of water ice and hydrated minerals.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov.

Voir l'image PIA00846: NIMS E4 Observations of Europa Trailing Hemisphere sur le site de la NASA.

PIA02590: Europa's Frozen Surface

Europa, a moon of Jupiter, appears as a thick crescent in this enhanced-color image from NASA's Galileo spacecraft, which has been orbiting Jupiter since 1995.

The view combines images taken in violet, green and near-infrared filters in 1998 and 1995. The colors have been stretched to show the subtle differences in materials that cover the icy surface of Europa. Reddish linear features are some of the cracks and ridges, thousands of kilometers long, which are caused by the tides raised by the gravitational pull of Jupiter. Mottled, reddish "chaotic terrain" exists where the surface has been disrupted and ice blocks have moved around. The red material at the ridges and chaotic terrain is a non-ice contaminant and could be salts brought up from a possible ocean beneath Europa's frozen surface.

Also visible are a few circular features, which are small impact craters. Europa's surface has very few craters, indicating that recent or current geologic activity has removed the traces of older impacts. The paucity of craters, coupled with other evidence, has led scientists to surmise that there could be an ocean of liquid water beneath Europa's surface. Where there is water, there could be life. This is why Europa is a target of current interest for study of the possibility of non-Earth life. A follow-up spacecraft to Galileo will be Europa Orbiter, which should determine whether or not Europa has an ocean.

While at the University of Arizona, Tucson, Dr. Cynthia Phillips used this image in a detailed search for current geologic activity on Europa. Phillips is currently with the SETI Institute, Mountain View, Calif. For a study published in the Journal of Geophysical Research -- Planets last year, she compared the frames that make up this image with similar images taken in 1979 by the Voyager spacecraft and found no sign of changes due to geologic activity. That suggests a minimum surface age for Europa of about 30 million years, though the result does not rule out current geologic activity altogether, as the study was limited by the resolution of 2 kilometers (1.6 miles) or more per pixel in this image and the Voyager images. Future images by Europa Orbiter may allow a search for smaller-scale changes on Europa's surface.

The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo and Voyager missions for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/.

Voir l'image PIA02590: Europa's Frozen Surface sur le site de la NASA.

PIA00834: NIMS G1 Observation of Europa

The Near Infrared Mapping Spectrometer (NIMS) on the Galileo spacecraft imaged most of Europa, including the north polar regions, at high spectral resolution at a range of 156,000 km (97,500 miles) during the G1 encounter on June 28 1996. The image on the right shows Europa as seen by NIMS, centered on 25 degrees N latitude, 220 W longitude. This is the hemisphere that always faces away from Jupiter. The image on the left shows the same view point from the Voyager data (from the encounters in 1979 and 1980). The NIMS image is in the 1.5 micron water band, in the infrared part of the spectrum. Comparison of the two images, infrared to visible, shows a marked brightness contrast in the NIMS 1.5 micron water band from area to area on the surface of Europa, demonstrating the sensitivity of NIMS to compositional changes. NIMS spectra show surface compositions ranging from pure water ice to mixtures of water and other minerals which appear bright in the infrared.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/galileo/sepo.

Voir l'image PIA00834: NIMS G1 Observation of Europa sur le site de la NASA.

PIA01127: Europa - Ice Rafting View

View of a small region of the thin, disrupted, ice crust in the Conamara region of Jupiter's moon Europa showing the interplay of surface color with ice structures. The white and blue colors outline areas that have been blanketed by a fine dust of ice particles ejected at the time of formation of the large (26 kilometer in diameter) crater Pwyll some 1000 kilometers to the south. A few small craters of less than 500 meters or 547 yards in diameter can be seen associated with these regions. These were probably formed, at the same time as the blanketing occurred, by large, intact, blocks of ice thrown up in the impact explosion that formed Pwyll. The unblanketed surface has a reddish brown color that has been painted by mineral contaminants carried and spread by water vapor released from below the crust when it was disrupted. The original color of the icy surface was probably a deep blue color seen in large areas elsewhere on the moon. The colors in this picture have been enhanced for visibility.

North is to the top of the picture and the sun illuminates the surface from the right. The image, centered at 9 degrees north latitude and 274 degrees west longitude, covers an area approximately 70 by 30 kilometers (44 by 19 miles), and combines data taken by the Solid State Imaging (CCD) system on NASA's Galileo spacecraft during three of its orbits through the Jovian system. Low resolution color (violet, green, and infrared) data acquired in September 1996, were combined with medium resolution images from December 1996, to produce synthetic color images. These were then combined with a high resolution mosaic of images acquired on February 20th, 1997 at a resolution of 54 meters (59 yards) per picture element and at a range of 5340 kilometers (3320 miles).

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. JPL is a division of California Institute of Technology (Caltech).

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA01127: Europa - Ice Rafting View sur le site de la NASA.

PIA00016: Europa - Full Disk

PIA00877: Agenor Linea on Europa

This image of Europa's southern hemisphere was obtained by the solid state imaging (CCD) system on board NASA's Galileo spacecraft during its sixth orbit of Jupiter. The upper portion of the image shows the southern extent of the "wedges" region, an area that has undergone extensive disruption. South of the wedges, part of Agenor Linea (nearly 1000 kilometers in length) is also visible. Agenor Linea is unique in that it is similar in width and length to the dark bands seen in the northern hemisphere, but it is bright in color rather than dark. This area will be studied at higher resolution on one of Galileo's later orbits, which should help scientists explain Agenor's bright color. This image can be used by scientists to make a global map of Europa by tying such Galileo images together with images from 1979 during NASA's Voyager mission. Such lower resolution images also provide the context needed to interpret the higher resolution images taken by the Galileo spacecraft during both its nominal mission and the upcoming Europa mission.

North is to the top of the picture and the sun illuminates the surface from the right. The image, centered at 40 degrees south latitude and 210 west longitude, covers an area approximately 675 by 675 kilometers. The finest details that can discerned in this picture are about 3.3 kilometers across. The images were taken on Feb 20, 1997 at 12 hours, 55 minutes, 34 seconds Universal Time when the spacecraft was at a range of 81,707 kilometers.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA00877: Agenor Linea on Europa sur le site de la NASA.

PIA01183: Europa Wedge Region

This image shows an area of crustal separation on Jupiter's moon, Europa. Lower resolution pictures taken earlier in the tour of NASA's Galileo spacecraft revealed that dark wedge-shaped bands in this region are areas where the icy crust has completely pulled apart. Dark material has filled up from below and filled the void created by this separation.

In the lower left corner of this image, taken by Galileo's onboard camera on December 16, 1997, a portion of one dark wedge area is visible, revealing a linear texture along the trend of the wedge. The lines of the texture change orientation slightly and reflect the fact that we are looking at a bend in the wedge. The older, bright background, visible on the right half of the image, is criss-crossed with ridges. A large, bright ridge runs east-west through the upper part of the image, cutting across both the older background plains and the wedge. This ridge is rough in texture, with numerous small terraces and troughs containing dark material.

North is to the top of the picture and the sun illuminates the surface from the northwest. This image, centered at approximately 16.5 degrees south latitude and 196.5 degrees west longitude, covers an area approximately 10 kilometers square (about 6.5 miles square). The resolution of this image is about 26 meters per picture element. This image was taken by the solid state imaging system from a distance of 1250 kilometers (750 miles).

PIA01092: Geologic Evidence of Internal Activity on Europa

This six frame mosaic of Europa's surface shows a variety of interesting geologic features. The prominent "X" near the center of the mosaic is the junction of two "triplebands." Triplebands are seen here to be made up of parallel sets of ridges, and can be traced for over 1,600 kilometers (off the image) across Europa's surface. Directly to the south of the "X" is a 75 by 100 kilometer (km) area where the icy crust of Europa has been disrupted by activity from below. This activity could be motion in liquid water, convection in warm ice, or some other process. Many icy blocks, some as large as 10 km across, have been rafted from the edges of this zone. Also seen in this mosaic are various pits and domes that range in size from a few kilometers to nearly 20 km across. These geologic features provide evidence of thermal activity below Europa's surface at the time that the features formed.

These images were obtained by the Solid State Imaging (CCD) system on NASA's Galileo spacecraft during its sixth orbit around Jupiter. North is to the top of the picture, with the sun illuminating the scene from the right. The center of this mosaic is located near 10 degrees north latitude, 271 degrees west longitude. The image, which is about 300 by 300 km across, was acquired at a resolution of 180 meters per picture element.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov.

Voir l'image PIA01092: Geologic Evidence of Internal Activity on Europa sur le site de la NASA.

PIA02861: Europa and Callisto under the watchful gaze of Jupiter

One moment in an ancient, orbital dance is caught in this color picture taken by NASA's Cassini spacecraft on Dec. 7, 2000, just as two of Jupiter's four major moons, Europa and Callisto, were nearly perfectly aligned with each other and the center of the planet.

The distances are deceiving. Europa, seen against Jupiter, is 600,000 kilometers (370,000 miles) above the planet's cloud tops. Callisto, at lower left, is nearly three times that distance from the cloud tops. Europa is a bit smaller than Earth's Moon and has one of the brightest surfaces in the solar system. Callisto is 50 percent bigger -- roughly the size of Saturn's largest satellite, Titan -- and three times darker than Europa. Its brightness had to be enhanced in this picture, relative Europa's and Jupiter's, in order for Callisto to be seen in this image.

Europa and Callisto have had very different geologic histories but share some surprising similarities, such as surfaces rich in ice. Callisto has apparently not undergone major internal compositional stratification, but Europa's interior has differentiated into a rocky core and an outer layer of nearly pure ice. Callisto's ancient surface is completely covered by large impact craters: The brightest features seen on Callisto in this image were discovered by the Voyager spacecraft in 1979 to be bright craters, like those on our Moon. In contrast, Europa's young surface is covered by a wild tapestry of ridges, chaotic terrain and only a handful of large craters.

Recent data from the magnetometer carried by the Galileo spacecraft, which has been in orbit around Jupiter since 1995, indicate the presence of conducting fluid, most likely salty water, inside both worlds.

Scientists are eager to discover whether the surface of Saturn's Titan resembles that of Callisto or Europa, or whether it is entirely different when Cassini finally reaches its destination in 2004.

Cassini is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini mission for NASA's Office of Space Science, Washington, D.C.

Voir l'image PIA02861: Europa and Callisto under the watchful gaze of Jupiter sur le site de la NASA.

PIA01664: Three dimensional view of Double Ridges on Europa

These images reveal the dramatic topography of Europa's icy crust. North is to the right. An east-west running double ridge with a deep intervening trough cuts across older background plains and the darker wedge shaped band. The numerous cracks and bands of such terrain may indicate where the crust has pulled apart and sometimes allowed dark material from beneath the surface to well up and fill the cracks. A computer generated three dimensional perspective (upper right) shows that bright material, probably pure water ice, prevails at the ridge crests and slopes while most dark material (perhaps ice mixed with silicates or hydrated salts) is confined to lower areas such as valley floors. The northernmost (right) slope which faces north, however, has a larger concentration of dark material than south facing slopes. The model on the lower right has been color coded to accentuate elevations. The red tones indicate that the crests of the ridge system reach elevations of more than 300 meters (330 yards) above the surrounding furrowed plains (blue and purple tones). The two ridges are separated by a valley about 1.5 kilometers (0.9 miles) wide.

The stereo perspective combines high resolution images obtained from two different viewing angles. Such a three dimensional model is similar to the three dimensional scenes our brains construct when both eyes view something from two angles.

North is to the right, and the sun illuminates the scene from northwest. The images were taken by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft. The regional context (left), centered at about 16 degrees south latitude, 195 degrees west longitude, was imaged on November 6th, 1996 at a range of about 41,000 kilometers (25,500 miles). The higher resolution stereo images were taken on December 16th, 1997, at ranges of 5,800 kilometers(3,600 miles) and 2,600 kilometers (1,600 miles) leading to a best resolution of 26 meters per picture element.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.

Voir l'image PIA01664: Three dimensional view of Double Ridges on Europa sur le site de la NASA.

PIA02528: Europa's Jupiter-Facing Hemisphere

This 12-frame mosaic provides the highest resolution view ever obtained of the side of Jupiter's moon Europa that faces the giant planet. It was obtained by the camera onboard NASA's Galileo spacecraft on November 25, 1999 during the spacecrafts 25th orbit of Jupiter.

The new images have resolutions of about 1 kilometer (0.6 miles) per picture element. Lower resolution context was provided by images acquired during earlier Galileo orbits. In the earlier images, the resolution is 7 and 13 kilometers (4 and 8 miles) per picture element, respectively.

Numerous linear features in the center of the mosaic and toward the poles may have formed in response to tides strong enough to fracture Europa's icy surface. Some of these features extend for over 1,500 kilometers (900 miles). Darker regions near the equator on the eastern (right) and western (left) limb may be vast areas of chaotic terrain. Bright white spots near the western limb are the ejecta blankets of young impact craters.

North is to the top of the picture and the sun illuminates the surface from the left. The image, centered at 0 latitude and 10 longitude, covers an area approximately 2,500 by 3,000 kilometers. The finest details that can discerned in this picture are about 2 kilometers across (about 1,550 by 1,860 miles). The images were taken by Galileo's camera on November 25, 1999 when the spacecraft was 94,000 kilometers (58,000 miles) from Europa.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.

This image and other images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.

Voir l'image PIA02528: Europa's Jupiter-Facing Hemisphere sur le site de la NASA.

PIA00325: Europa Crescent

PIA01178: High-Resolution Image of Europa's Ridged Plains

This spectacular image taken by NASA's Galileo spacecraft camera shows a region of ridged plains on Jupiter's moon Europa. The plains are comprised of many parallel and cross-cutting ridges, commonly in pairs. The majority of the region is of very bright, but darker material is seen primarily in valleys between ridges. Some of the most prominent ridges have dark deposits along their margins and in their central valleys. Some of this dark material probably moved down the flanks of the ridges and has piled up along their bases. The most prominent ridges are about a kilometer in width (less than a mile). In the top right hand corner of the image the end of a dark wide ridge (about 2 kilometers or 1.2 miles across) is visible. Several deep fractures cut through this ridge and continue into the plains. The brightness of the region suggests that frost covers much of Europa's surface. This image looks different from those obtained earlier in Galileo's mission, because this image was taken with the Sun higher in Europa's sky.

This image was taken on December 16, 1997 at a range of 1,300 kilometers (800 miles) by Galileo's solid state imaging system. North is to the top of the picture, and the Sun illuminates the surface from the upper left. This image, centered at approximately 14 degrees south latitude and 194 degrees west longitude, covers an area approximately 20 kilometers (12 miles) on each side. The resolution is 26 meters (85 feet) per picture element.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/ galileo.

Voir l'image PIA01178: High-Resolution Image of Europa's Ridged Plains sur le site de la NASA.

PIA00853: Europa 6th Orbit NIMS Data

PIA01176: Europa's Pwyll Crater

This view of the Pwyll impact crater on Jupiter's moon Europa taken by NASA's Galileo spacecraft shows the interior structure and surrounding ejecta deposits. Pwyll's location is shown in the background global view taken by Galileo's camera on December 16, 1997. Bright rays seen radiating from Pwyll in the global image indicate that this crater is geologically young. The rim of Pwyll is about 26 kilometers (16 miles) in diameter, and a halo of dark material excavated from below the surface extends a few kilometers beyond the rim. Beyond this dark halo, the surface is bright and numerous secondary craters can be seen. The closeup view of Pwyll, which combines imaging data gathered during the December flyby and the flyby of February 20, 1997, indicates that unlike most fresh impact craters, which have much deeper floors, Pwyll's crater floor is at approximately the same level as the surrounding background terrain.

North is to the top of the picture and the sun illuminates the surface from the northeast. This closeup image, centered at approximately 26 degrees south latitude and 271 degrees west longitude, covers an area approximately 125 by 75 kilometers (75 by 45 miles). The finest details that can be discerned in this picture are about 250 meters (800 feet) across. This image was taken on at a range of 12,400 kilometers (7,400 miles), with the green filter of Galileo's solid state imaging system.

PIA01084: Flow-like Features On Europa

This image shows features on Jupiter's moon Europa that may be "flows" from ice volcanoes. It was taken by the Galileo spacecraft solid state imaging (CCD) system during its seventh orbit around Jupiter. North is to the top of the image. The sun illuminates the scene from the left, showing features with shapes similar to lava flows on Earth. Two such features can be seen in the northwest corner of the image. The southern feature appears to have flowed over a ridge along its western edge. Scientists use these types of relationships to determine which feature formed first. In this case, the ridge probably formed before the flow-like feature that covers it.

The image, centered at 22.6 degrees north latitude and 106.7 degrees west longitude, covers an area of 180 by 215 kilometers (112 by 134 miles). The smallest distinguishable features in the image are about 1.1 kilometers (0.7 miles) across. This image was obtained on April 28, 1997, when Galileo was 27,590 kilometers (16,830 miles) from Europa.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA01084: Flow-like Features On Europa sur le site de la NASA.

PIA00502: Natural and False Color Views of Europa

This image shows two views of the trailing hemisphere of Jupiter's ice-covered satellite, Europa. The left image shows the approximate natural color appearance of Europa. The image on the right is a false-color composite version combining violet, green and infrared images to enhance color differences in the predominantly water-ice crust of Europa. Dark brown areas represent rocky material derived from the interior, implanted by impact, or from a combination of interior and exterior sources. Bright plains in the polar areas (top and bottom) are shown in tones of blue to distinguish possibly coarse-grained ice (dark blue) from fine-grained ice (light blue). Long, dark lines are fractures in the crust, some of which are more than 3,000 kilometers (1,850 miles) long. The bright feature containing a central dark spot in the lower third of the image is a young impact crater some 50 kilometers (31 miles) in diameter. This crater has been provisionally named "Pwyll" for the Celtic god of the underworld.

Europa is about 3,160 kilometers (1,950 miles) in diameter, or about the size of Earth's moon. This image was taken on September 7, 1996, at a range of 677,000 kilometers (417,900 miles) by the solid state imaging television camera onboard the Galileo spacecraft during its second orbit around Jupiter. The image was processed by Deutsche Forschungsanstalt fuer Luftund Raumfahrt e.V., Berlin, Germany.

The Jet Propulsion Laboratory, Pasadena, CA, manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the Galileo mission home page on the World Wide Web at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo.

Voir l'image PIA00502: Natural and False Color Views of Europa sur le site de la NASA.

PIA01401: Scrambled Ice

This complex area on the side of Europa which faces away from Jupiter shows several types of features which are formed by disruptions of Europa's icy crust. North is to the top of the image, taken by NASA's Galileo spacecraft, and the Sun illuminates the surface from the left. The prominent wide, dark bands are up to 20 kilometers (12 miles) wide and over 50 kilometers (30 miles) long. They are believed to have formed when Europa's icy crust fractured, separated and filled in with darker, "dirtier" ice or slush from below. A relatively rare type of feature on Europa is the 15-kilometer-diameter (9.3-mile) impact crater in the lower left corner. The small number of impact craters on Europa's surface is an indication of its relatively young age. A region of chaotic terrain south of this impact crater contains crustal plates which have broken apart and rafted into new positions. Some of these "ice rafts" are nearly 1 kilometer (about half a mile) across. Other regions of chaotic terrain are visible and indicate heating and disruption of Europa's icy crust from below. The youngest features in this scene are the long, narrow cracks in the ice which cut across all other features. One of these cracks is about 30 kilometers (18 miles) to the right of the impact crater and extends for hundreds of miles from the top to the bottom of the image.

The image, centered near 23 degrees south latitude and 179 degrees longitude, covers an area about 240 by 215 kilometers (150 by 130 miles) across. The finest details that can be discerned in this picture are about 460 meters (500 yards) across. The image was taken as Galileo flew by Europa on March 29, 1998. The image was taken by the onboard solid state imaging system camera from an altitude of 23,000 kilometers (14,000 miles).

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA01401: Scrambled Ice sur le site de la NASA.

PIA01406: Topography within Europa's Mannann'an crater

This three dimensional effect is created by superimposing images of Jupiter's icy moon, Europa, which were taken from slightly different perspectives. When viewed through red (left eye) and blue (right eye) filters, this product, a stereo anaglyph, shows variations in height of surface features.

This view shows the rim and interior of the impact crater Mannann'an, on Jupiter's moon Europa. The stereo image reveals the rim of the crater which appears as a tall ridge near the left edge of the image, as well as and numerous small hills on the bottom of the crater. One of the most striking features is the large pit surrounded by circular cracks on the right side of the image, with dark radiating fractures in its center.

The right (blue) image is a high resolution image (20 meters per picture element) taken through a clear filter. The left (red) image is composed of lower resolution (80 meters per picture element) color images taken through violet, green, and near-infrared filters and averaged to approximate an unfiltered view.

North is to the top of the picture and the sun illuminates the scene from the east (right). The image, centered at 3 degrees north latitude and 120 degrees west longitude, covers an area approximately 18 by 4 kilometers (11 by 2.5 miles). The finest details that can be discerned in this picture are about 40 meters (44 yards) across. The images were taken on March 29th, 1998 at 13 hours, 17 minutes, 29 seconds Universal Time at a range of 1934 kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA01406: Topography within Europa's Mannann'an crater sur le site de la NASA.

PIA01647: Agenor Linea in Color

Agenor Linea is an unusually bright, white band on Jupiter's icy moon Europa. This mosaic uses color images to "paint" high resolution images of Agenor, and then places the colorized images within lower resolution images of the surrounding area. All data was obtained on September 26th, 1998 during the 17th orbit of Jupiter by NASA's Galileo spacecraft. Along this portion of Agenor is a "triple band," flanked by dark, reddish material of uncertain origin. On the right side of this image, Agenor splits into two sections. These color images will help scientists understand why Agenor Linea is unusually bright and white compared to Europa's other ridges and bands.

North is to the upper right of the picture and the sun illuminates the surface from the east. The image, centered at 41 degrees south latitude and 189 degrees west longitude, covers an area approximately 135 by 60 kilometers (84 by 37 miles). The highest resolution images were obtained at a resolution of about 50 meters (165 feet) per picture element and are shown here in context at about 220 meters per picture element. The images were taken by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft at a range of about 4700 kilometers (2900 miles) for the highest resolution images and less than 20000 kilometers (12,400 miles) for the lower resolution color images.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URLhttp://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo.

Voir l'image PIA01647: Agenor Linea in Color sur le site de la NASA.

PIA00542: Prominent Doublet Ridges on Europa

This image of Jupiter's satellite Europa was obtained from a range of 7364 miles (11851 km) by the Galileo spacecraft during its fourth orbit around Jupiter and its first close pass of Europa. The image spans 30 miles by 57 miles (48 km x 91 km) and shows features as small as 800 feet (240 meters) across, a resolution more than 150 times better than the best Voyager coverage of this area. The sun illuminates the scene from the right. The large circular feature in the upper left of the image could be the scar of a large meteorite impact. Clusters of small craters seen in the right of the image may mark sites where debris thrown from this impact fell back to the surface. Prominent doublet ridges over a mile (1.6 km) wide cross the plains in the right part of the image; younger ridges overlap older ones, allowing the sequence of formation to be determined. Gaps in ridges indicate areas where emplacement of new surface material has obliterated pre-existing terrain.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

PIA00539: Jupiter's Icy Satellite Europa

This image of Europa, an icy satellite of Jupiter, was obtained from a range of 39028 miles (62089 kilometers) by the Galileo spacecraft during its fourth orbit around Jupiter and its first close pass of Europa. The image spans an area 157 miles by 244 miles (252 km by 393 km), and shows features as small as a mile (1.6 km) across. Sun illumination is from the right, revealing several ridges crossing the scene, plateaus commonly several miles (10 km) across, and patches of smooth, low-lying darker materials. No prominent impact craters are visible, indicating the surface in this location is not geologically ancient. Some ridges have gaps, and subtle textural differences in these areas indicate that missing ridge segments probably were swept away by volcanic flows. The flow deposits are probably composed mainly of water ice, the chief constituent of the surface of Europa.

The Galileo mission is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, Washington, D.C.

This image and other images and data received from Galileo are posted on the Galileo mission home page on the World Wide Web at http://galileo.jpl.nasa.gov/. Background information and educational context for the images can be found at http://www2.jpl.nasa.gov/galileo/sepo/.

Voir l'image PIA00539: Jupiter's Icy Satellite Europa sur le site de la NASA.

PIA01640: Mitten shaped region of Chaotic Terrain on Europa

This view of Jupiter's icy moon Europa shows a region shaped like a mitten that has a texture similar to the matrix of chaotic terrain, which is seen in medium and high resolution images of numerous locations across Europa's surface. Development of such terrain may be one of the major processes for resurfacing the moon. North is to the top and the sun illuminates the surface from the left. The material in the "catcher's mitt" has the appearance of frozen slush and seems to bulge upward from the adjacent surface, which has been bent downward and cracked, especially along the southwest (lower left) margins. Scientists on the Galileo imaging team are exploring various hypotheses for the formation of such terrain including solid-state convection (vertical movement between areas which differ in density due to heating), upwelling of viscous icy "lava," or liquid water melting through from a subsurface ocean.

The image, centered at 20 degrees north latitude, 80 degrees west longitude covers an area approximately 175 by 180 kilometers (108 by 112 miles). The resolution is 235 meters per picture element. The images were taken on 31 May, 1998 Universal Time at a range of 23 thousand kilometers (14 thousand miles) by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo.

Voir l'image PIA01640: Mitten shaped region of Chaotic Terrain on Europa sur le site de la NASA.

PIA01665: Red-Blue Three dimensional view of Pwyll crater

This three dimensional effect is created by superimposing images of Jupiter's moon, Europa, which were taken from two slightly different perspectives. When viewed through red (left eye) and blue (right eye) filters, the product, an anaglyph, shows variations in height of surface features.

The anaglyph shows Pwyll crater on Jupiter's icy satellite Europa. The crater is about 26 kilometers (16 miles) across and has a central peak which rises approximately 600 meters (almost 2,000 feet) above the crater floor. The heavily degraded rim reaches a height of only 300 meters. A central peak that is higher than the crater rim is unusual among other craters in the Solar System. A continuous ejecta blanket around the impact structure rises above the surrounding landscape and is at about the same topographic level as the crater floor. The Pwyll impact appears to have occurred on a northwest to southeast (upper left to lower right) trending slope.

North is to the top of the picture. Pwyll is located at about 25 degrees south latitude and 271 degrees west longitude. The stereo perspective combines high resolution images obtained from two different camera positions. Such a three dimensional model is similar to the three dimensional scenes our brains construct from images seen by the left and right eyes. The picture is based on such a computer generated model using images taken by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft on two separate orbits. The grey band running completely across the image just north of Pwyllis where a gap in the data prevented three dimensional modelling. The images of Pwyll were taken from different viewing geometries on February 20, 1997 and December 16, 1997 at ranges of 13,200 kilometers (8,200 miles) and 13,500 kilometers (8,400 miles).

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URLhttp://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo.

Voir l'image PIA01665: Red-Blue Three dimensional view of Pwyll crater sur le site de la NASA.

PIA01662: Topography around Europa's Cilix crater

This shaded relief highlights relative elevations around Cilix crater on Jupiter's moon, Europa. North is to the top of the picture which was created by shading a model of the surface with the brightnesses resulting from artificial illumination. The sun illumination was artificially computed to be shining from the right (east) while 60 degrees above the horizon. Several images of Cilix, obtained at varying viewing geometries are combined to calculate a three dimensional surface model.

The Cilix impact structure is situated at about 180 degrees longitude near Europa's equator. The crater is 20 kilometers (12 miles) across, with rims as high as 500 meters (545 yards). The massif near the crater center is as high as the rim. While the western portion of the rim shows pronounced slumping of the crater walls, the opposite rim does not. The crater floor appears to have rebounded into a domed shape. Linear ridges in the shaded relief may be double ridges which are not fully resolved by the topographic model.

The stereo perspective combines images obtained from different camera positions. Such a three dimensional model is similar to the three dimensional scenes our brains construct from images seen by the left and right eyes. The figure uses uniformly grey patches, outlined in black, to indicate locations where gaps in the data prevented three dimensional modelling. The best resolution is 65 meters per picture element. The stereo images were taken on May 31st, 1998 at ranges of 12,300 kilometers (7,650 miles) and 4,500 kilometers (2,800 miles) by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URLhttp://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo.

Voir l'image PIA01662: Topography around Europa's Cilix crater sur le site de la NASA.

PIA01182: Very High Resolution Image of Icy Cliffs on Europa

This image, taken by the camera onboard NASA's Galileo spacecraft, is a very high resolution view of the Conamara Chaos region on Jupiter's moon Europa. It shows an area where icy plates have been broken apart and moved around laterally. The top of this image is dominated by corrugated plateaus ending in icy cliffs over a hundred meters (a few hundred feet) high. Debris piled at the base of the cliffs can be resolved down to blocks the size of a house. A fracture that runs horizontally across and just below the center of the Europa image is about the width of a freeway.

North is to the top right of the image, and the sun illuminates the surface from the east. The image is centered at approximately 9 degrees north latitude and 274 degrees west longitude. The image covers an area approximately 1.7 kilometers by 4 kilometers (1 mile by 2.5 miles). The resolution is 9 meters (30 feet) per picture element. This image was taken on December 16, 1997 at a range of 900 kilometers (540 miles) by Galileo's solid state imaging system.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/ galileo.

Voir l'image PIA01182: Very High Resolution Image of Icy Cliffs on Europa sur le site de la NASA.

PIA01295: Europa Global Views in Natural and Enhanced Colors

This color composite view combines violet, green, and infrared images of Jupiter's intriguing moon, Europa, for a view of the moon in natural color (left) and in enhanced color designed to bring out subtle color differences in the surface (right). The bright white and bluish part of Europa's surface is composed mostly of water ice, with very few non-ice materials. In contrast, the brownish mottled regions on the right side of the image may be covered by hydrated salts and an unknown red component. The yellowish mottled terrain on the left side of the image is caused by some other unknown component. Long, dark lines are fractures in the crust, some of which are more than 3,000 kilometers (1,850 miles) long.

North is to the top of the picture and the sun fully illuminates the surface. Europa is about 3,160 kilometers (1,950 miles) in diameter, or about the size of Earth's moon. The finest details that can be discerned are 25 kilometers across. The images in this global view were taken in June 1997 at a range of 1.25 million kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft, during its ninth orbit of Jupiter.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA01295: Europa Global Views in Natural and Enhanced Colors sur le site de la NASA.

PIA02099: Thera and Thrace on Europa

Thera and Thrace are two dark, reddish regions of enigmatic terrain that disrupt the older icy ridged plains on Jupiter's moon Europa. North is toward the top of the mosaic obtained by NASA's Galileo spacecraft. Thera (left) is about 70 kilometers wide by 85 kilometers high (43 by 53 miles) and appears to lie slightly below the level of the surrounding plains. Some bright icy plates which are observed inside appear to be dislodged from the edges of the chaos region. The curved fractures along its boundaries suggest that collapse may have been involved in Thera's formation. In contrast, Thrace (right) is longer, shows a hummocky texture, and appears to stand at or slightly above the older surrounding bright plains. Thrace abuts the gray band Libya Linea to the south and appears to darken Libya. One model for the formation of these and other chaos regions on Europa is complete melt-through of Europa's icy shell from an ocean below. Another model is that warm ice welled up from below and caused partial melting and disruption of the surface.

To produce this image, two regional images obtained at a resolution of 220 meters (240 yards) per picture element during Galileo's 17th orbit of Jupiter were colorized with lower resolution (1.4 kilometers or 1526 yards per picture element) images of the region obtained during the 14th orbit. The color image is generated from the violet, green, and near-infrared (968 nanometers) filters of the Galileo Solid State Imaging system and exaggerates the subtle color differences of Europa's surface. The mosaic, centered at about 50 degrees south latitude and 180 degrees longitude, covers an area approximately 525 by 300 kilometers (325 by 186 miles). The images from the 17th orbit were acquired at Universal Time 02 hours, 51 minutes, 56 seconds on September 26, 1998 when the sun illuminated the region from the northeast.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

Voir l'image PIA02099: Thera and Thrace on Europa sur le site de la NASA.

PIA01126: High Resolution Mosaic of Ridges, Plains, and Mountains on Europa

This mosaic shows some of the highest resolution images obtained by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft during its eleventh orbit around Jupiter. North is to the top of the image. The sun illuminates the scene from the left, showing hundreds of ridges that cut across each other, indicating multiple episodes of ridge formation either by volcanic or tectonic activity within the ice. Also visible in the image are numerous isolated mountains or "massifs." The highest of these, located in the upper right corner and lower center of the mosaic, are approximately 500 meters (1,640 feet) high. Irregularly shaped areas where the ice surface appears to be lower than the surrounding plains (e.g., in the left-center and lower left corner of the mosaic) may be related to the "chaos" areas of iceberg-like features seen in earlier SSI images of Europa.

The mosaic, centered at 35.4 degrees north latitude and 86.8 degrees west longitude, covers an area of 108 kilometers by 90 kilometers (66 miles by 55 miles). The smallest distinguishable features in the image are about 68 meters (223 feet) across. These images were obtained on November 6, 1997, when the Galileo spacecraft was approximately 3,250 kilometers (1,983 miles) from Europa.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. JPL is a division of California Institute of Technology.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA01126: High Resolution Mosaic of Ridges, Plains, and Mountains on Europa sur le site de la NASA.

PIA00544: Ridges on Europa

This is the highest resolution picture ever taken of the Jupiter moon, Europa. The area shown is about 5.9 by 9.9 miles (9.6 by 16 kilometers) and the smallest visible feature is about the size of a football field. In this view, the ice-rich surface has been broken into a complex pattern by cross-cutting ridges and grooves resulting from tectonic processes. Sinuous rille-like features and knobby terrain could result from surface modifications of unknown origins. Small craters of possible impact origin range in size from less than 330 feet (100 meters) to about 1300 feet (400 meters) across are visible.

This image was taken by the solid state imaging television camera aboard the Galileo during its fourth orbit around Jupiter, at a distance of 2060 miles (3340 kilometers). The picture is centered at 325 degrees West, 5.83 degrees North. North is toward the top of this image, with the sun shining from the right.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

PIA00595: Icy Europa and similar scales on Earth

This is the first in a series of products that compare images at increasing resolutions of various areas on Jupiter's icy moon Europa (top frame) to the same location on Earth, the San Francisco Bay area of California (bottom frame). Both images show areas of roughly equal size, 252 by 393 kilometers (157 by 244 miles), and resolution, 630 meters (690 yards). This means that the smallest identifiable feature is less than a mile across (2 pixels wide). North is to the top of the picture.

The sun illumination from the right in the Europa image reveals several ridges crossing the scene, plateaus commonly several miles (10 km) across, and patches of smooth, low-lying darker materials. No prominent impact craters are visible, indicating the surface in this location is not geologically ancient. Some ridges have gaps, and subtle textural differences in these areas indicate that missing ridge segments probably were swept away by volcanic flows. The flow deposits are probably composed mainly of water ice, the chief constituent of the surface of Europa.

The Earth based image (lower frame) covers an area stretching from San Francisco Bay (top left) to the Nevada border (top right) and from Mono Lake in (top center) to the Mojave Desert (bottom right). Other predominant geographic features include the snow capped Sierra Nevada Mountains and California's Great Central Valley (center frame).

The Europa image was obtained from a range of 62089 kilometers (39028 miles) by the Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft on December 19th, 1996 (Universal Time). The San Francisco Bay area image, from the NOAA satellite's Advanced Very High Resolution Radiometer (AVHRR) instrument, has been reprocessed to roughly match Galileo's resolution so as to offer a sense of the size of the features visible on Europa's surface.

The Jet Propulsion Laboratory, Pasadena, CA, manages the mission for NASA's Office of Space Science, Washington D.C. This image and other images and data received from Galileo are posted on the World Wide Web Galileo mission home page at: http://galileo.jpl.nasa.gov.

Voir l'image PIA00595: Icy Europa and similar scales on Earth sur le site de la NASA.

PIA01641: Double Ridges, Dark Spots, and Smooth Icy Plains on Europa

This mosaic of a region in the northern hemisphere of Jupiter's moon, Europa, displays many of the features which are typical on the satellite's icy surface. Brown, linear (double) ridges extend prominently across the scene. They could be frozen remnants of cryovolcanic activity which occurred when water or partly molten water ice erupted on the Europan surface, freezing almost instantly in the extremely low temperatures so far from our sun. Dark spots, several kilometers in diameter, are distributed over the surface. A geologically older, smoother surface, bluish in tone, underlies the ridge system. The blue surface is composed of almost pure water ice, whereas the composition of the dark, brownish spots and ridges is not certain. One possibility is that they contain evaporites such as mineral salts in a matrix of high water content.

North is to the lower left of the picture and the sun illuminates the surface from the upper left. The image, centered at 40 degrees north latitude and 225 degrees west longitude, covers an area approximately 800 by 350 kilometers(500 by 220 miles). The resolution is 230 meters (250 yards) per picture element. The colors have been enhanced to bring out the details. An astronaut orbiting this smallest of the four Galilean satellites would seethe icy surface of Europa somewhat brighter, but with less intense colors. The images were obtained during two separate orbits of Jupiter by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft. High resolution images obtained at a range of about 25,000 kilometers(15,000 miles) during the spacecraft's 15th orbit of Jupiter on May 31st, 1998 are combined with http://www.jpl.nasa.gov/galileo/sepo./atjup/europa/G1.html">lower resolution images obtained during the spacecraft's first orbit of Jupiter on June 28th, 1996. Combining the lower resolution and high resolution images enables scientists to investigate both the surface features in great detail as well as the color or compositional information in a regional context.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission or NASA's Office of Space Science, Washington, DC.

PIA01130: Interior of Europa

Cutaway view of the possible internal structure of Europa The surface of the satellite is a mosaic of images obtained in 1979 by NASA's Voyager spacecraft. The interior characteristics are inferred from gravity field and magnetic field measurements by NASA's Galileo spacecraft. Europa's radius is 1565 km, not too much smaller than our Moon's radius. Europa has a metallic (iron, nickel) core (shown in gray) drawn to the correct relative size. The core is surrounded by a rock shell (shown in brown). The rock layer of Europa (drawn to correct relative scale) is in turn surrounded by a shell of water in ice or liquid form (shown in blue and white and drawn to the correct relative scale). The surface layer of Europa is shown as white to indicate that it may differ from the underlying layers. Galileo images of Europa suggest that a liquid water ocean might now underlie a surface ice layer several to ten kilometers thick. However, this evidence is also consistent with the existence of a liquid water ocean in the past. It is not certain if there is a liquid water ocean on Europa at present.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

PIA01646: Agenor Linea at High Resolution

Agenor Linea is an unusual feature on Jupiter's icy moon Europa since it is brighter than its surroundings while most of Europa's ridges and bands are relatively dark. During the Galileo spacecraft's 17th orbit of Jupiter, high resolution images were obtained of Agenor Linea near Europa's day/night boundary so as to emphasize fine surface details. This mosaic shows high resolution images embedded in slightly lower resolution images which were also acquired during the 17th orbit. The Galileo images show that Agenoris not a ridge, but is relatively flat. Its interior consists of several long bands, just one of which is the very bright feature known as Agenor. Each long band shows fine striations along its length. A few very small craters pockmark Agenor Linea and its surroundings. Agenor is cut by some narrow fractures, and by some small subcircular features called lenticulae. Rough chaotic terrain is visible at the top and bottom of this photo, and appears to be "eating away" at the edges of Agenor. Though previously it was suspected that Agenor Linea might be one of the youngest features on Europa, this new view shows that it is probably not.

North is to the upper right of the picture and the sun illuminates the surface from the east. The image, centered at 44 degrees south latitude and 219 degrees west longitude, covers an area approximately 130 by 95 kilometers (80 by 60 miles). The highest resolution images were obtained at a resolution of about 50 meters (165 feet) per picture element and are shown here in context at about 220 meters per picture element. The images were taken on September 26th, 1998 at ranges as close as 5000 kilometers (3100 miles) by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.

Voir l'image PIA01646: Agenor Linea at High Resolution sur le site de la NASA.

PIA00543: Structurally Complex Surface of Europa

This is a composite of two images of Jupiter's icy moon Europa obtained from a range of 2119 miles (3410 kilometers) by the Galileo spacecraft during its fourth orbit around Jupiter and its first close pass of Europa. The mosaic spans 11 miles by 30 miles (17 km by 49 km) and shows features as small as 230 feet (70 meters) across. This mosaic is the first very high resolution image data obtained of Europa, and has a resolution more than 50 times better than the best Voyager coverage and 500 times better than Voyager coverage in this area. The mosaic shows the surface of Europa to be structurally complex. The sun illuminates the scene from the right, revealing complex overlapping ridges and fractures in the upper and lower portions of the mosaic, and rugged, more chaotic terrain in the center. Lateral faulting is revealed where ridges show offsets along their lengths (upper left of the picture). Missing ridge segments indicate obliteration of pre-existing materials and emplacement of new terrain (center of the mosaic). Only a small number of impact craters can be seen, indicating the surface is not geologically ancient.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

PIA00592: Close-up of Europa's Surface

This close-up view of the icy surface of Europa, a moon of Jupiter, was obtained on December 20, 1996, by the Solid State Imaging system on board the Galileo spacecraft during its fourth orbit around Jupiter. The view is about 11 kilometers by 16 kilometers (7 miles by 10 miles) and has a resolution of 26 meters (28 yards). The Sun illuminates the scene from the east (right).

A flat smooth area about 3.2 kilometers (2 miles) across is seen in the left part of the picture. This area resulted from flooding by a fluid which erupted onto the surface and buried sets of ridges and grooves. The smooth area contrasts with a distinctly rugged patch of terrain farther east, to the right of the prominent ridge system running down the middle of the picture. The rugged patch of terrain is 4 kilometers (2.5 miles) across and represents localized disruption of the complex network of ridges in the area. Eruptions of material onto the surface, crustal disruption, and the formation of complex networks of folded and faulted ridges show that significant energy was available in the interior of Europa. Although small impact craters are most easily seen in the smooth area, they occur throughout the ridged terrain seen in this view.

The Jet Propulsion Laboratory, Pasadena, CA, manages the mission for NASA's Office of Space Science, Washington D.C. This image and other images and data received from Galileo are posted on the World Wide Web Galileo mission home page at: http://galileo.jpl.nasa.gov.

Voir l'image PIA00592: Close-up of Europa's Surface sur le site de la NASA.

PIA01407: Europa Imaging Highlights during GEM

During the two year Galileo Europa Mission (GEM), NASA's Galileo spacecraft will focus intensively on Jupiter's intriguing moon, Europa. This montage shows samples of some of the features that will be imaged during eight successive orbits. The images in this montage are in order of increasing orbit from the upper left (orbit 11) to the lower right (orbit 19).

DESCRIPTIONS AND APPROXIMATE RESOLUTIONSTriple bands and dark spots

1.6 kilometers/pixelConamara Chaos

1.6 kilometers/pixelMannan'an Crater

1.6 kilometers/ pixelCilix

1.6 kilometers/pixelAgenor Linea and Thrace Macula

2 kilometers/pixelSouth polar terrain

2 kilometers/pixelRhadamanthys Linea

1.6 kilometers/pixelEuropa plume search

7 kilometers/pixel< /tr>

1. Triple bands and dark spots were the focus of some images from Galileo's eleventh orbit of Jupiter. Triple bands are multiple ridges with dark deposits along the outer margins. Some extend for thousands of kilometers across Europa's icy surface. They are cracks in the ice sheet and indicate the great stresses imposed on Europa by tides raised by Jupiter, as well as Europa's neighboring moons, Ganymede and Io. The dark spots or "lenticulae" are spots of localized disruption.

2. The Conamara Chaos region reveals icy plates which have broken up, moved, and rafted into new positions. This terrain suggests that liquid water or ductile ice was present near the surface. On Galileo's twelfth orbit of Jupiter, sections of this region with resolutions as high as 10 meters per picture element will be obtained.

3. Mannann'an Crater is a feature newly discovered by Galileo in June 1996. Color and high resolution images (to 40 meters per picture element) from Galileo's fourteenth orbit of Jupiter will offer a close look at the crater and help characterize how impacts affect the icy surface of this moon.

4. Cilix, a large mound about 1.5 kilometers high, is the center of Europa's coordinate system. Its concave top and what may be flow like features to the southwest of the mound are especially intriguing. The origin of this feature is unknown at present. Color, stereo, and high resolution images (to 65 meters per picture element) from Galileo's fifteenth orbit of Jupiter will offer new insights and resolve questions about its origin.

5. Images of Agenor Linea (white arrow) and Thrace Macula (black arrow) with resolutions as high as 30 meters per picture element will be obtained during Galileo's sixteenth orbit of Jupiter. Agenor is an unusually bright lineament on Europa. Is the brightness due to new ice, and if so, does it represent recent activity? Could the dark region of Thrace Macula be a flow from ice volcanism?

6. Images of Europa's south polar terrain obtained during Galileo's seventeenth orbit of Jupiter will offer insights into the processes which are active in this region. Is the ice crust thicker near Europa's poles than near the equator? The prominent dark line running from upper left to lower right through the center of this image is Astypalaea Linea. It is a fault about the length of the San Andreas fault in California and is the largest such fault known on Europa. Images with resolutions of 48 meters per picture element will be obtained to examine its geologic structure.

7. This long lineament, Rhadamanthys Linea. is spotted with dark "freckles." Are these freckle features formed by icy volcanism? Is this an early form of a triple band? Stereo and high resolution (to 46 meters per picture element) obtained during Galileo's eighteenth orbit of Jupiter may indicate whether the lineament is the result of volcanic processes or is formed by other surface processes.

8. During Galileo's nineteenth orbit of Jupiter, images of Europa will be taken with very low sun illuminations, similar to taking a picture at sunset or sunrise. The object will be to search for backlit plumes issuing from icy volcanic vents. Such plumes would be direct evidence of a liquid ocean beneath the ice. Resolutions will be as high as 40 meters per picture element. This picture was simulated image from Galileo data obtained during the spacecraft's second orbit of Jupiter in September 1996.

North is to the top of the pictures. During orbit 13, the Galileo spacecraft was behind the sun from our vantage point on Earth so it did not obtain or transmit data from that orbit. The left two images in the bottom row were obtained by NASA's Voyager 2 spacecraft in 1979; the remaining images were obtained by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft in 1996.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA01407: Europa Imaging Highlights during GEM sur le site de la NASA.

PIA02960: Folds on Europa

This image, acquired by NASA's Galileo spacecraft on September 26, 1998, shows features on the surface of Jupiter's moon Europa that a scientific report published today interprets as signs of compressive folding.

The imaged area is in the Astypalaea Linea region of Europa's southern hemisphere, seen with low-angle sunshine coming from the upper right. North is toward the top.

Astypalaea Linea is the smooth, gray area that stretches from north to south across the image mosaic. It is thought to have formed by a combination of pulling apart and sliding of the icy surface. The telltale fold features are within the smoother portions of the surface between the more dominant ridges, which are attributed to upwelling of material through surface ice. In the smooth areas, the surface has gentle swells and dips, which show most clearly in the version on the right, processed to accentuate broader-scale shapes. For example, a dip about 15 kilometers (about 10 miles) wide cuts diagonally across the northern half of the largest smooth area, and a rise runs parallel to that in the southern half of the smooth area.
closeup detail

Louise M. Prockter, at Johns Hopkins University, and Robert T. Pappalardo, at Brown University, report in the journal Science today that those rises, or anticlines, and dips, or synclines, appear to be the result of compression causing the crust to fold.

Additional evidence comes from smaller features more visible in the version on the left, covering the same area. At the crest of the gentle rise in the largest smooth area are small fractures that could be caused by the stretching stress of bending the surface layer upwards. Similarly, at the bottom of the adjacent dip are small, wrinkle-like ridges that could be caused by stress from bending the surface layer downwards.

The Jet Propulsion Laboratory, Pasadena, Calif., manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology, Pasadena, Calif.

Voir l'image PIA02960: Folds on Europa sur le site de la NASA.

PIA00702: Ancient Impact Basin on Europa

This feature on Europa was seen as a dark, diffuse circular patch on a previous Galileo global image of Europa's leading hemisphere on April 3, 1997. The "bulls-eye" pattern appears to be a 140- kilometer (86-mile) wide impact scar (about the size of the island of Hawaii) which formed as the surface fractured minutes after a mountain-sized asteroid or comet slammed into the satellite. This approximately 214-kilometer (132-mile) wide picture is the product of three images which have been processed in false color to enhance shapes and compositions.

North is toward the top of this picture, which is illuminated from sunlight coming from the west. This color composite reveals a sequence of events which have modified the surface of Europa. The earliest event was the impact which formed the Tyre structure at 34 degrees north latitude and 146.5 degrees west longitude. The impact was followed by the formation of the reddish lines superposed on Tyre. The red color designates areas that are probably a dirty water ice mixture. The fine blue-green lines crossing the region from west to east appear to be ridges which formed after the crater.

The images were taken on April 4, 1997, at a resolution of 595 meters (1950 feet) per picture element and a range of 29,000 kilometers (17,900 miles). The images were taken by Galileo's solid state imaging (CCD) system.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA00702: Ancient Impact Basin on Europa sur le site de la NASA.

PIA01523: Europa Linear Features from 246,000 kilometers

The first close look ever obtained of Jupiter's satellite, Europa, was taken today, July 9, by Voyager 2 as the spacecraft approached the planet. The linear crack-like features had been seen from a much greater distance last March by Voyager 1. This picture was made at a range of 246,000 kilometers (152,000 miles) and provides a resolution of about four kilometers (2.5 miles). The complicated linear features appear even more like cracks or huge fractures in these images. Also seen are somewhat darker mottled regions which appear to have a slightly pitted appearance, perhaps due to small scale craters. No large craters (more than five kilometers in diameter) are easily identifiable in the Europa photographs to date, suggesting that this satellite has a young surface relative to Ganymede and Callisto, although not perhaps as young as Io's. Various models for Europa's structure will be tested during analysis of these images, including the possibility that the surface is a thin ice crust overlying water or softer ice and that the fracture systems seen are breaks in that crust. Resurfacing mechanisms such as production of fresh ice or snow along the cracks and cold glacier-like flows are being considered as possibilities for removing evidence of impact events. Europa thus appears to truly be a satellite with many properties intermediate between Ganymede and Io.

Voir l'image PIA01523: Europa Linear Features from 246,000 kilometers sur le site de la NASA.

PIA01633: The Tyre multi-ring Structure on Europa

This mosaic shows the Tyre multi-ring structure which is thought to have been formed by a large impact onto Jupiter's moon Europa. The effective crater (large bull's-eye feature) is about 40 kilometers (25 miles) across while the entire structure is much larger. The feature was formerly known as Tyre Macula. The concentric rings, of which five to seven can be discerned easily, consist of troughs and ridges. Tyre is one of the few impact structures on Europa that has concentric rings and may indicate an area where fluid material, perhaps liquid water, lay below the surface at the time of impact. A few ridges within Tyre appear to have been partly destroyed at the time of impact.

North is to the top of the picture and the sun illuminates the surface from the left. The mosaic is centered at 34 degrees north latitude and 144 degrees west longitude and covers an area approximately 424 by 456 kilometers (265 by 285 miles). The resolution is 170 meters (185 feet) across. The horizontal and vertical black lines in the mosaic indicate gaps in the data received for this image. The images were taken on March 29, 1998 at a range of approximately 18,000 kilometers (11,250 miles) by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission or NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo.

Voir l'image PIA01633: The Tyre multi-ring Structure on Europa sur le site de la NASA.

PIA00291: Europa's Broken Ice

Jupiter's moon Europa, as seen in this image taken June 27, 1996 by NASA's Galileo spacecraft, displays features in some areas resembling ice floes seen in Earth's polar seas. Europa, about the size of Earth's moon, has an icy crust that has been severely fractured, as indicated by the dark linear, curved, and wedged-shaped bands seen here. These fractures have broken the crust into plates as large as 30 kilometers (18.5 miles) across. Areas between the plates are filled with material that was probably icy slush contaminated with rocky debris. Some individual plates were separated and rotated into new positions. Europa's density indicates that it has a shell of water ice as thick as 100 kilometers (about 60 miles), parts of which could be liquid. Currently, water ice could extend from the surface down to the rocky interior, but the features seen in this image suggest that motion of the disrupted icy plates was lubricated by soft ice or liquid water below the surface at the time of disruption. This image covers part of the equatorial zone of Europa and was taken from a distance of 156,000 kilometers (about 96,300 miles) by the solid-state imager camera on the Galileo spacecraft. North is to the right and the sun is nearly directly overhead. The area shown is about 360 by 770 kilometers (220-by-475 miles or about the size of Nebraska), and the smallest visible feature is about 1.6 kilometers (1 mile) across. The Jet Propulsion Laboratory manages the Galileo mission for NASA's Office of Space Science.

Voir l'image PIA00291: Europa's Broken Ice sur le site de la NASA.

PIA09246: Europa

PIA00275: Europa In Color

False color has been used here to enhance the visibility of certain features in this composite of three images of the Minos Linea region on Jupiter's moon Europa taken on 28 June 1996 Universal Time by the solid state imaging camera on NASA's Galileo spacecraft. Triple bands, lineae and mottled terrains appear in brown and reddish hues, indicating the presence of contaminants in the ice. The icy plains, shown here in bluish hues, subdivide into units with different albedos at infrared wavelengths probably because of differences in the grain size of the ice. The composite was produced using images with effective wavelengths at 989, 757, and 559 nanometers. The spatial resolution in the individual images ranges from 1.6 to 3.3 kilometers (1 to 2 miles) per pixel. The area covered, centered at 45N, 221 W, is about 1,260 km (about 780 miles) across.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA00275: Europa In Color sur le site de la NASA.

PIA00578: Europa Ice Floes

Jupiter's moon Europa, as seen in this image taken June 27, 1996 by NASA's Galileo spacecraft, displays features in some areas resembling ice floes seen in Earth's polar seas. Europa, about the size of Earth's moon, has an icy crust that has been severely fractured, as indicated by the dark linear, curved, and wedged-shaped bands seen here. These fractures have broken the crust into plates as large as 30 kilometers (18.5 miles) across. Areas between the plates are filled with material that was probably icy slush contaminated with rocky debris. Some individual plates were separated and rotated into new positions. Europa's density indicates that it has a shell of water ice thicker than 100 kilometers (about 60 miles), parts of which could be liquid. Currently, water ice could extend from the surface down to the rocky interior, but the features seen in this image suggest that motion of the disrupted icy plates was lubricated by soft ice or liquid water below the surface at the time of disruption. This image covers part of the equatorial zone of Europa and was taken from a distance of 156,000 kilometers (about 96,300 miles) by the Solid-state Imaging Subsystem on the Galileo spacecraft. North is to the right and the sun is nearly directly overhead. The area shown is about 510 by 989 kilometers (310-by-600 miles), and the smallest visible feature is about 1.6 kilometers (1 mile) across.

The Jet Propulsion Laboratory manages the Galileo mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web Galileo mission home page at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http:// www.jpl.nasa.gov/galileo/sepo.

Voir l'image PIA00578: Europa Ice Floes sur le site de la NASA.

PIA00852: Dome shaped features on Europa's surface

PIA01177: Chaotic Terrain on Europa in Very High Resolution

This view of the Conamara Chaos region on Jupiter's moon Europa taken by NASA's Galileo spacecraft shows an area where the icy surface has been broken into many separate plates that have moved laterally and rotated. These plates are surrounded by a topographically lower matrix. This matrix material may have been emplaced as water, slush, or warm flowing ice, which rose up from below the surface. One of the plates is seen as a flat, lineated area in the upper portion of the image. Below this plate, a tall twin-peaked mountain of ice rises from the matrix to a height of more than 250 meters (800 feet). The matrix in this area appears to consist of a jumble of many different sized chunks of ice. Though the matrix may have consisted of a loose jumble of ice blocks while it was forming, the large fracture running vertically along the left side of the image shows that the matrix later became a hardened crust, and is frozen today. The Brooklyn Bridge in New York City would be just large enough to span this fracture.

North is to the top right of the picture, and the sun illuminates the surface from the east. This image, centered at approximately 8 degrees north latitude and 274 degrees west longitude, covers an area approximately 4 kilometers by 7 kilometers (2.5 miles by 4 miles). The resolution is 9 meters (30 feet) per picture element. This image was taken on December 16, 1997 at a range of 900 kilometers (540 miles) by Galileo's solid state imaging system.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/ galileo.

Voir l'image PIA01177: Chaotic Terrain on Europa in Very High Resolution sur le site de la NASA.

PIA01212: Near-Terminator Image of Europa

This image of Europa's surface was obtained by the Solid State Imaging (CCD) system on board NASA's Galileo spacecraft during its fourth orbit of Jupiter, Linear features with bright central stripes referred to as "triple bands" are seen to transect the surface of Europa. Several of these triple bands are over 700 kilometers in length. In the left side of the image the surface of Europa is seen to be locally pitted and irregular. Ridges less than 100 kilometers in length are also visible in this region.

The area seen in this image, centered near 27 degrees South, 300 degrees West, is 760 kilometers (456 miles) by 850 kilometers (510 miles) across, which is approximately the size of the state of Texas or the country of France. North is to the top of the image, with the sun illuminating the surface from the left. The image which has a resolution of 1.3 kilometers per picture element (pixel) was obtained on December 19th, 1996 (Universal Time).

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA01212: Near-Terminator Image of Europa sur le site de la NASA.

PIA03002: Blocks in the Europan Crust Provide More Evidence of Subterranean Ocean

PIA01179: Dark and Bright Ridges on Europa

This high-resolution image of Jupiter's moon Europa, taken by NASA's Galileo spacecraft camera, shows dark, relatively smooth region at the lower right hand corner of the image which may be a place where warm ice has welled up from below. The region is approximately 30 square kilometers in area. An isolated bright hill stands within it. The image also shows two prominent ridges which have different characteristics; youngest ridge runs from left to top right and is about 5 kilometers in width (about 3.1 miles). The ridge has two bright, raised rims and a central valley. The rims of the ridge are rough in texture. The inner and outer walls show bright and dark debris streaming downslope, some of it forming broad fans. This ridge overlies and therefore must be younger than a second ridge running from top to bottom on the left side of the image. This dark ~2 km wide ridge is relatively flat, and has smaller-scale ridges and troughs along its length.

North is to the top of the picture, and the sun illuminates the surface from the upper left. This image, centered at approximately 14 degrees south latitude and 194 degrees west longitude, covers an area approximately 15 kilometers by 20 kilometers (9 miles by 12 miles). The resolution is 26 meters (85 feet) per picture element. This image was taken on December 16, 1997 at a range of 1300 kilometers (800 miles) by Galileo's solid state imaging system.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/ galileo.

Voir l'image PIA01179: Dark and Bright Ridges on Europa sur le site de la NASA.

PIA01102: Terrain on Europa under Changing Lighting Conditions

These images obtained by the Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft show the same region of Europa under different lighting conditions. The upper image was obtained on June 28th, 1996 during Galileo's first orbit around Jupiter under "high-sun" conditions -- the equivalent of taking a picture from a high altitude at noon (with the sun directly overhead). Note that albedo (light/dark) features are emphasized. Compare this to the lower image containing a higher-resolution inset. This (inset) image was taken on November 6th, 1996 during the spacecraft's third orbit under "low-sun" illumination -- the equivalent of taking a picture from a high altitude at sunrise or sunset. Note that in this image the albedo features are not readily apparent. Instead, the topography of the terrain is emphasized. Planetary geologists use information from images acquired under a variety of lighting conditions to identify different types of structures and interpret how they formed. Note that the bright linear features in the upper image are seen to be ridges in the lower image. The circular feature on the right side of both images, Cilix, is approximately 25 kilometers (15 miles) across.

The area seen in the upper image is 312 kilometers (187 miles) by 570 kilometers (342 miles) across; the area covered by the inset is 36 kilometers (22 miles) by 315 kilometers (190 miles) across. Both of these images are centered near 2 South latitude, 185 West longitude. North is to the top of the frames.

The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..

Voir l'image PIA01102: Terrain on Europa under Changing Lighting Conditions sur le site de la NASA.